ES2928395T3 - Therapeutic compositions comprising deuterated or partially deuterated N,N-dimethyltryptamine compounds - Google Patents

Abstract

The present invention provides a deuterated N,N-dimethyltryptamine compound or a plurality of deuterated N,N-dimethyltryptamine compounds for use in therapy, selected from N,N-dimethyltryptamine, α-protium, α-deutero-N, N-dimethyltryptamine compounds, α,α-dideutero-N,N-dimethyltryptamine compounds, and pharmaceutically acceptable salts of these compounds, preferably wherein the deuterated N,N-dimethyltryptamine compound has an increased half-life compared to the half-life from the undeuterated N,N. N-dimethyltryptamine. In particular, the invention provides a compound of Formula I, or a pharmaceutically acceptable salt thereof; (I) where the ratio of deuterium:protium in the compound is greater than that found naturally in hydrogen; each R1 is independently selected from H and D; R2 is selected from CH3 and CD3; R3 is selected from CH3 and CD3; and each yH is independently selected from H and D. Also provided are methods of synthesizing compounds of the present invention and methods of using such compositions in the treatment of psychiatric or neurological disorders, such as major depressive disorder. (Automatic translation with Google Translate, without legal value)

Description

DESCRIPTION

Therapeutic compositions comprising deuterated or partially deuterated N,N-dimethyltryptamine compounds

field of invention

The present invention provides a deuterated N,N-dimethyltryptamine compound for use in therapy.

In particular the invention provides a compound of formula I, or a pharmaceutically acceptable salt thereof, for use in therapy;

where:

R1 is selected from H and D;

R2 is CD3;

R3 is selected from CH3 and CD3; Y

both andH are D.

Also provided are methods of synthesizing compounds of the present invention, compositions comprising said compounds, and methods of using said compounds in the treatment of psychiatric or neurological disorders, such as major depressive disorder.

Background of the invention

Classic psychedelics have shown preclinical and clinical promise in the treatment of psychiatric disorders (Carhart-Harris and Goodwin (2017), The Therapeutic Potential of Psychedelic Drugs: Past, Present and Future, Neuropsychopharmacology 42, 2105-2113). In particular, psilocybin has shown significant improvement on a variety of depression and anxiety rating scales in double-blind randomized studies (Griffiths et al. (2016), Psilocybin produces substantial and sustained decreases in depression and anxiety in patients with life—threatening cancer: a randomized double-blind trial, Journal of Psychopharmacology 30(12), 1181-1197).

N,N-Dimethyltryptamine (DMT) is also understood to have therapeutic value as a short-acting psychedelic, however its duration of action (less than 20 minutes) is so short as to limit effective therapy. Administration protocols have been developed to extend the immersive psychedelic experience of DMT (Gallimore and Strassman (2016), A model for the application of target—controlled intravenous infusion for a prolonged immersive DMT psychedelic experience, Frontiers in Pharmacology, 7:211). . However, these protocols carry the risk of toxicant accumulation in patients who are poor metabolizers of DMT (for more information, see Strassman et al. (1994), Dose response study of N,N—dimethyltryptamine in humans, Arch Gen Psychiatry 51, 85). a,a,p,p—tetradeutero-N,N—dimethyltryptamine is known to exhibit a kinetic isotope effect that confers a significant difference in its in vivo pharmacokinetic profile compared to N,N—dimethyltryptamine. Substitution of hydrogen with a deuterium on a central sp3 carbon is known to give rise to a "kinetic isotope effect" by virtue of the difference in bond strength between a CH bond and a CD bond. First demonstrated in 1982 (Barkery et al. (1982), Comparison of the brain levels of N,N—dimethyltryptamine and a,a,p,p—tetradeutero— N,N—dimethyltryptamine following intraperitoneal injection, Biochemical Pharmacology, 31(15 ), 2513—2516), the half-life of a,a,p,p—tetradeutero-N,N—dimethyltryptamine in the brain of rodents suggests that administration of a,a,p,p—tetradeutero-N, N-dimethyltryptamine alone would keep a patient in the DMT space for longer than is therapeutically essential.

WO 2021/089873 (prior art according to article 54(3) EPC) describes the synthesis of compounds of formula III from compounds of formula I via compounds of formula II:

where each xH is independently selected from protium and deuterium, n is selected from 0, 1, 2, 3, or 4, R1 is independently selected from —R3, -O3, —O(CO)R3, —F, —CI, —Br or —I, and R2 and R3 independently of C1-C4alkyl. Also disclosed are the compounds of formula III, or pharmaceutically acceptable salts thereof, obtainable by the method, as well as compositions comprising such compounds.

WO 2021/089872 A1 (prior art according to article 54(3) EPC) describes compounds of formula I or pharmaceutically acceptable salts thereof:

where xH is protium or deuterium,

n is selected from 1, 2, 3 or 4,

R1 is selected regardless of —R3, —OR3, —O(CO)R3, —F, —CI, —Br, or —I, and

R2 and R3 are independently selected from C1—C4 alkyl. Compositions comprising such compounds are also described.

Document WO 2020/245133 A1 (prior art according to article 54(3) EPC) describes compositions comprising N,N-dimethyltryptamine, deuterated N,N-dimethyltryptamine and/or partially deuterated N,N-dimethyltryptamine. Methods for synthesizing said compositions and methods of using said compositions in the treatment of psychiatric or psychocognitive disorders are also described.

Morris and others. ("Indolealkylamine metabolism: Synthesis of deuterated indolealkylamines as metabolic probes", Journal of Labeled Compounds & Radiopharmaceuticals, vol. 33, no. 6, 1993, pages 455—465) describes the synthesis of deuterium-labeled indolealkylamine hallucinogens of endogenous origin , N,N-dimethyltryptamine and

5-methoxy-N,N-dimethyltryptamine by reduction of amide intermediates with lithium aluminum deuteride.

WO 2019/081764 A1 describes a combination product comprising (i) a compound that promotes neurogenesis but has hallucinogenic or psychedelic side effects, and (ii) a 5-HT2A receptor antagonist.

Brain levels of the compound a,a,p,p-tetradeutero-N,N-dimethyltryptamine have been reported by Barker and others as a function of time and dose (Biochemical Pharmacology, 1982, vol. 31, no. 15, pp 2513-2516).

Behavioral effects of the compounds a,a-dideutero-N,N-dimethyltryptamine or a,a,p,p-tetradeutero-N,N-dimethyltryptamine were reported by Beaton et al. in rats on a food-reinforced program (Pharmacology Biochemistry and Behavior, 1982, Vol 16, No 5, pp. 811-814).

Morris et al. reported the synthesis of the compounds a,a,p,p—tetradeutero-N,N—dimethyltryptamine, a,a—dideutero-N,N—dimethyltryptamine, and a,a—dideutero-5-methoxy—N,N —dimethyltryptamine (Journal of Labeled Compounds and Radiopharmaceuticals, 1993, vol. 33, no. 6, pp. 455-465).

Summary of the invention

The present invention is based, in part, on the ability to apply knowledge of the kinetic isotope effect exhibited by a,a,p,p-tetradeutero-N,N-dimethyltryptamine to modify, in a controlled manner, the pharmacokinetic profile of N, N —dimethyltryptamine, allowing for a more flexible therapeutic application. In particular, by providing compositions of individual drug substances comprising the deuterated analogues of N,N-dimethyltryptamine, in particular N,N-dimethyltryptamine comprising two deuterium atoms in the alpha position (i.e., attached to the carbon atom to which the dimethylamino moiety is attached) and comprising deuteration at the N,N—dimethyl positions, the present invention provides compositions and methods that allow a single dose to maintain a patient in total dissociation from the outside world, referred to herein as the "DMT space", for a therapeutically optimized duration without relying on infusion protocols or combination therapy with monoamine oxidase inhibitors in the clinic. The present invention provides a clinically applicable solution that reduces clinical complexity and increases clinical flexibility in the delivery of DMT-assisted therapy.

In addition, we have observed a quantifiable relationship between the degree of deuteration and, by proxy, the H:D ratio of the input reducing agent in the synthetic methods described herein, and the effect on potentiation (ie, increase) of the metabolic half-life of the parent compound. Said technical effect can be used to quantifiably increase the precision with which N,N—dimethyltryptamine (i.e., isolated deuterium) compositions containing the N,N—dimethyltryptamine compounds or compositions comprising more than one selected compound type were deuterated of N,N-dimethyltryptamine and its deuterated analogues, in particular those deuterated at the alpha and N,N-dimethyl positions, or their pharmaceutically acceptable salts). Viewed from a first aspect, the invention provides a deuterated N,N-dimethyltryptamine compound of formula (I) for use in therapy:

where the ratio of deuterium:protium in the compound is greater than that found naturally in hydrogen:

R1 is selected from H and D;

R2 is CD3;

R3 is selected from CH3 and CD3; Y

both andH are D,

or a pharmaceutically acceptable salt thereof.

In preferred embodiments of the first aspect R1 is H. In some embodiments of the first aspect R3 is CD3. Viewed from a second aspect, the invention provides a method for synthesizing a compound of formula (I) or a pharmaceutically acceptable salt thereof, which comprises reacting a compound of formula (II) with LiAlD4,

where R1 is selected from H and D,

R2 is and CD3;

R3 is selected from CH3 and CD3;

and both and H are D.

Viewed from a third aspect, the invention provides a pharmaceutical composition comprising a compound as defined according to any of the first to second aspects in combination with a pharmaceutically acceptable excipient.

Viewed from a fourth aspect, the invention provides a compound or composition as defined according to any of the first to third aspects for use in a method of psychedelic-assisted psychotherapy. Viewed from a fifth aspect, the invention provides a compound or composition as defined according to any one of the first to fourth aspects for use in a method of treating a neurological disorder or a psychological disorder in a patient.

Viewed from a sixth aspect, the invention provides a method of preparing a compound according to any of the first or second aspects of the invention comprising contacting deuterated 2-(3-indolyl)-N,N-dimethylacetamide with an agent reductant consisting essentially of aluminum deuteride and lithium. Viewed from a seventh aspect, the invention provides compound 1, or a pharmaceutically acceptable salt thereof, for use in therapy.

Other aspects and embodiments of the present invention will become apparent from the discussion that follows below.

Brief description of the figures

Figure 1 represents the predicted pharmacokinetic profile of partially deuterated DMT compared to undeuterated DMT and fully deuterated DMT. A) predicted plasma concentration and B) concentration in brain tissue, showing the extended half-life of partially deuterated DMT. The hatched area represents effect site concentrations (>60 ng/mL) that are experienced as complete dissociation from the outside world, known as the "DMT space."

Figure 2 plots the half-life of plots calculated in vitrn for DMT and 6 deuterate-containing compositions described in reference example 1. A) Linear regression analysis. The value of r2 for the half-life is 0.754; where the slope was found to be significantly different from zero, p=0.01. B) Half-life of deuterated analogs as a change in percent of (undeuterated) DMT (dashed line). Figure 3 In vitrn intrinsic clearance for DMT and 6 deuterium-containing compositions described in reference example 1. A) Linear regression analysis. The r2 value for intrinsic clearance is 0.7648; where the slope was found to be significantly different from zero, p=0.01. B) Intrinsic clearance of deuterated analogs as percent change in DMT (undeuterated) (dashed line).

Figure 4 In vitrn intrinsic clearance (A) and half-life (B) of DMT (SPL026) and 6 different mixtures of deuterated D2 analogs of SPL028 in human hepatocytes with and without mAo-A/B inhibitor combination, as described in the examples section below.

Figures 1 through 4 are presented for illustrative purposes only.

Detailed description of the invention

Throughout this specification, one or more aspects of the invention may be combined with one or more features described in the specification to define different embodiments of the invention.

References in the present description to a singular of a noun encompass the plural of the noun, and vice versa, unless the context otherwise implies.

Throughout this description the word "comprising", or variations such as "comprising" or "comprising", is understood to imply the inclusion of a declared element, integer or stage, or group of elements, integers or stages, but not the exclusion of any other element, integer or stage, or group of elements, integers or stages.

The present invention provides a deuterated N,N-dimethyltryptamine compound selected from the a,a-dideutero-N,N-dimethyltryptamine compounds having deuteration at the N,N-dimethyl positions and pharmaceutically acceptable salts of these compounds for use in therapy.

As used herein, the term "deuterated N,N-dimethyltryptamine compound" means an N,N-dimethyltryptamine compound having a deuterium composition greater than that found naturally in hydrogen (about 1.6%). As used in the present description, the term "non-deuterated N, N -dimethyltryptamine compound" means an N,N -dimethyltryptamine compound having a deuterium composition equal to or less than that found naturally in hydrogen.

The inventors have discovered that the compounds of the present invention exhibit a primary kinetic isotope effect when one or two deuterium atoms are placed on the alpha carbon of an N,N-dimethyltryptamine compound. This primary kinetic isotope effect is exhibited to its greatest extent by the a,a-dideutero-N,N-dimethyltryptamine compounds and, to a lesser extent, by the a-protio,a-deutero-N,N-dimethyltryptamine compounds, of such that the fold change in half-life of an a—protio,a—deutero— N,N -dimethyltryptamine compound compared to the N,N—dimethyltryptamine analog is approximately half that of the a,a—dideutero— analog N,N—dimethyltryptamine.

The inventors have also discovered that the compounds of the present invention exhibit a secondary kinetic isotope effect when the N,N-dimethyl groups are deuterated. When said N,N—dimethyl groups comprise one or more deuterium and the alpha position is also mono- or di-deuterated, the secondary kinetic isotope is synergistic with the effect of the primary kinetic isotope, producing a more than 14-fold increase in lifetime. mean compared to the undeuterated isotope N,N-dimethyltryptamine (see example 3).

N,N — dimethyltryptamine and all its deuterated analogues freely form addition salts with anionic counterions. Throughout the specification, an N,N-dimethyltryptamine compound also refers to any pharmaceutically acceptable salt, eg, the fumarate salt.

Typically, the acid reagents can be used to prepare salts, in particular pharmaceutically acceptable salts, of the N,N-dimethyltryptamine compounds. Examples of suitable acid reagents are selected from the group consisting of fumaric acid, hydrochloric acid, tartaric acid, citric acid, hydrobromic acid, sulfuric acid, phosphoric acid, acetic acid, maleic acid, lactic acid, tartaric acid, and gluconic acid. Often in the form of salts, the N,N-dimethyltryptamine compounds, in particular as the compounds of the invention, in the compositions of the invention or otherwise used in accordance with the various aspects of the present invention, and embodiments thereof, are fumarate, hydrochloride, tartrate or citrate salts, in particular fumarate salts.

Compounds of the first aspect of the invention, and indeed those of the second (and other, as appropriate) aspect of the invention, may be present in free base or salt form (such as the salts described herein), optionally as solvates (eg, hydrates) of these.

The description provides a composition obtainable by reducing a composition comprising 2-(3-indolyl)-N,N-dimethylacetamide with a reducing agent consisting essentially of lithium aluminum deuteride. In both aspects, the reducing agent can be dissolved or suspended in a liquid medium. Due to its strong reactivity with water and protective solvents such as alcohols, although it is available in solid (powdered) form, lithium aluminum deuteride is often handled in dry aprotic solvents such as ethers, often under an inert atmosphere. The expert is well aware of such precautions and proper protocols. The description also provides a composition obtained by such a reduction or, more generally, obtained by a reduction as described in the present description.

According to particular embodiments, by mentioning that the reducing agent consists essentially of lithium aluminum deuteride, it is meant that the reducing agent may comprise additional components but that the presence of these components will not materially affect the essential characteristics of the reducing agent (in particular, stability and reductionist propensity).

According to the third aspect of the invention, there is provided a pharmaceutical composition comprising a compound as defined according to the first or second aspect of the invention, in combination with a pharmaceutically acceptable excipient.

The pharmaceutical composition of the invention comprises a compound of the invention (according to any of its first or second aspects) in combination with one or more pharmaceutically acceptable excipients. Suitable pharmaceutical compositions can be prepared by those skilled in the art, with examples of pharmaceutically acceptable excipients including, but not limited to, those described in Genaro et al., Remmington: The Science and Practice of Pharmacy, 20th Edition, Lippincott, Williams, and Wilkins, 2000 ( specifically part 5: pharmaceutical manufacturing). Suitable excipients are also described in the Handbook of Pharmaceutical Excipients, 2nd Edition; editors A. Wade and P. J. Weller, American Pharmaceutical Association, Washington, The Pharmaceutical Press, London, 1994.

The pharmaceutical compositions of the invention are expected to show superior oral bioavailability compared to undeuterated N,N-dimethyltryptamine. Accordingly, a compound or composition of the present invention may be compressed or otherwise formulated into solid dosage units, such as tablets, capsules, orally disintegrating tablets, thin films, buccal patches, and buccal lozenges, or processed into capsules or suppositories. When formulated as a tablet that disintegrates via Orally, a compound or composition of the present invention is compatible with the Zydis® platform. A Zydis® tablet is produced by lyophilization or lyophilization of a free base compound or composition of the present invention in a matrix. The resulting product is very light. Such embodiments of a formulation comprise particles, preferably with a particle size of less than 50 µm, of a compound or composition of the present invention physically suspended in a water-soluble matrix which is then lyophilized. An orally disintegrating tablet formulated in this way dissolves rapidly when placed in the mouth.

By means of pharmaceutically suitable liquids, the compounds can also be prepared in solution, suspension, emulsion or spray form. For the manufacture of dosage units, including tablets, the use of conventional additives such as fillers, colorants, polymeric binders and the like is contemplated. In general, any pharmaceutically acceptable additive can be used.

Suitable fillers with which the pharmaceutical compositions may be prepared and administered include lactose, starch, cellulose and derivatives thereof, and the like, or mixtures thereof used in suitable amounts. For parenteral administration, aqueous suspensions, isotonic saline solutions, and sterile injectable solutions containing pharmaceutically acceptable dispersing and/or wetting agents, such as propylene glycol or butylene glycol, may be used.

For parenteral administration, aqueous solutions, isotonic saline solutions, and sterile injectable solutions containing pharmaceutically acceptable dispersing and/or wetting agents, such as propylene glycol or butylene glycol, may be used. Formulations suitable for inhalation, transdermal, mucosal or transmembrane administration comprise a free base of a deuterated N,N-dimethyltryptamine compound, typically with one or more biocompatible excipients. Such formulations achieve a longer lasting therapeutic effect than equivalent formulations of undeuterated N,N-dimethyltryptamine.

Thus, one aspect of the invention provides a parenteral formulation comprising a free base of a compound of formula I, wherein R1 is selected from H and D; R2 is CD3; R3 is selected from CH3 and CD3; and both andH are D.

Typically, the biocompatible excipient comprises a solvent. Preferably, the solvent is selected from any one or a combination of two or more of propylene glycol, glycerin, polyethylene glycol, water, ethanol, and triacetin. For preferred inhalable formulations, the solvent is selected from propylene glycol, glycerin, and polyethylene glycol, or a mixture of these. Preferably, the solvent is a mixture of propylene glycol and glycerin in a ratio of from about 50:50 to about 30:70 by weight. The concentration of the free base is from about 1 mg/mL to about 1000 mg/mL. Preferably, the biocompatible excipient comprises a taste masking agent.

In preferred embodiments, the formulation has an oxygen content of less than 2 ppm. In embodiments, the formulation is stored in a container adapted to prevent ultraviolet light penetration.

The invention also provides a pharmaceutical composition of the invention, in combination with suitable packaging material for the composition, the packaging material including instructions for use of the pharmaceutical composition.

The compositions of the invention are useful in therapy and can be administered to a patient in need thereof. As used herein, the term "patient" preferably refers to a human patient, but may also refer to a domestic mammal. The term does not cover laboratory mammals.

According to the fifth aspect of the invention, there is provided a compound or composition as defined according to any of the first to fourth aspects for use in a method of treating a psychiatric disorder or a neurological disorder in a patient. In embodiments of the fifth aspect of the present invention, the psychiatric or neurological disorder is selected from (i) an obsessive-compulsive disorder, (ii) a depressive disorder, (iii) a schizophrenia disorder, (iv) a schizotypal disorder, (v) ) an anxiety disorder, (vi) a substance abuse disorder, (vii) an apathetic disorder, and (viii) a brain injury disorder.

As used herein, the term "psychiatric disorder" is a clinically significant psychological or behavioral syndrome or pattern occurring in an individual that is associated with present distress (eg, a painful symptom) or disability (eg, a painful symptom). , impairment in one or more important areas of functioning) or with a significantly increased risk of suffering death, pain, disability, or a significant loss of freedom.

As used herein, the term "neurological disorder" means a disease of the central and peripheral nervous system.

Diagnostic criteria for the psychiatric and neurological disorders referred to herein are provided, for example, in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (D ^s M-5).

As used herein, the term "obsessive-compulsive disorder" is defined by the presence of either obsessions or compulsions, but commonly both. The symptoms may cause significant functional impairment and/or distress. An obsession is defined as an unwanted intrusive thought, image, or impulse that repeatedly enters a person's mind. Compulsions are repetitive behaviors or mental acts that a person feels compelled to perform. Typically, obsessive-compulsive disorder (OCD) manifests as one or more obsessions that drive the adoption of a compulsion. For example, an obsession with germs can lead to a compulsion to clean. A compulsion can be overt and observable by others, such as checking that a door is locked, or a covert mental act that cannot be observed, such as repeating a certain phrase in the mind.

As used herein, the term "depressive disorder" includes major depressive disorder, persistent depressive disorder, bipolar disorder, bipolar depression, and depression in terminally ill patients.

As used herein, the term "major depressive disorder" (MDD, also called major depression or clinical depression) is defined as the presence of five or more of the following symptoms over a period of two weeks or more (also called in the present description as a "major depressive episode"), most of the day, nearly every day:

• depressed mood, such as feeling sad, empty, or tearful (in children and adolescents, depressed mood can manifest as constant irritability);

significantly reduced interest or no pleasure in all or most activities;

Significant weight loss when not dieting, weight gain, or decreased or increased appetite (in children, weight gain is not as expected);

insomnia or increased desire to sleep;

either restlessness or slow behavior that can be noticed by others;

fatigue or loss of energy;

feelings of worthlessness or excessive or inappropriate guilt;

difficulty making decisions, or difficulty thinking or concentrating;

recurring thoughts of death or suicide, or a suicide attempt.

At least one of the symptoms must be a depressed mood or a loss of interest or pleasure.

Persistent depressive disorder, also known as dysthymia, is defined as a patient who has both of the following characteristics:

A. has a depressed mood most of the time almost every day for at least two years. Children and adolescents may have irritable mood and the period of time is at least one year.

B. While depressed, a person experiences at least two of the following symptoms:

• Either overeating or lack of appetite.

• Sleeping too much or having trouble sleeping.

• Fatigue, lack of energy.

• Low self-esteem.

• Difficulty concentrating or making decisions.

As used herein, the term "treatment-resistant depression" describes MDD that fails to achieve an adequate response to adequate treatment with standard of care therapy.

As used herein, "bipolar disorder," also known as manic-depressive illness, is a disorder that causes unusual changes in mood, energy, activity levels, and the ability to carry out daily tasks. .

There are two defined subcategories of bipolar disorder; they all involve clear changes in mood, energy, and activity levels. These moods range from periods of extremely "up," euphoric, and energetic behavior (known as manic episodes and defined below) to periods of very sad, "low," or hopeless (known as depressive episodes). Less severe manic periods are known as hypomanic episodes.

Bipolar I disorder—defined by manic episodes that last at least 7 days, or by manic symptoms that are so severe that the person requires immediate hospital care. Depressive episodes usually also occur, typically lasting at least 2 weeks. Depressive episodes with mixed features (having depression and manic symptoms at the same time) are also possible.

Bipolar II disorder—defined by a pattern of depressive episodes and hypomanic episodes, but not the full-blown manic episodes described above.

As used herein, "bipolar depression" is defined as an individual experiencing depressive symptoms with a prior or coexisting episode of manic symptoms, but who does not meet the clinical criteria for bipolar disorder.

As used herein, the term "anxiety disorder" includes generalized anxiety disorder, phobia, panic disorder, social anxiety disorder, and post-traumatic stress disorder.

"Generalized Anxiety Disorder" (GAD) as used herein means a chronic disorder characterized by long-lasting anxiety that is not focused on any object or situation. Those who suffer from GAD experience persistent, non-specific fear and worry, and worry excessively about everyday affairs. GAD is characterized by chronic excessive worry accompanied by three or more of the following symptoms: restlessness, fatigue, concentration problems, irritability, muscle tension, and sleep disturbances.

"Phobia" is defined as a persistent fear of an object or situation that the affected person will do everything possible to avoid, typically out of proportion to the actual danger it represents. If the feared object or situation cannot be completely avoided, the affected person will endure it with marked distress and significant interference with social or occupational activities.

A patient with "panic disorder" is defined as one who experiences one or more brief attacks (also called panic attacks) of intense terror and apprehension, often characterized by tremors, shivering, confusion, dizziness, nausea, and/or difficulty breathing. A panic attack is defined as a fear or discomfort that arises abruptly and reaches its peak in less than ten minutes.

"Social anxiety disorder" is defined as intense fear and avoidance of negative public scrutiny, public embarrassment, humiliation, or social interaction. Social anxiety often manifests specific physical symptoms, such as flushing, sweating, and slurred speech.

"Post-traumatic stress disorder" (PTSD) is an anxiety disorder that results from a traumatic experience. Post-traumatic stress can result from an extreme situation, such as combat, a natural disaster, rape, hostage-taking, child abuse, bullying, or even a serious accident. Common symptoms include hypervigilance, flashbacks, avoidance behaviors, anxiety, anger, and depression.

As used herein, the term "substance abuse" means a patterned use of a drug in which the user consumes the substance in amounts or in methods that are harmful to himself or others.

As used herein, the term "avolitional disorder" refers to a disorder that includes as a symptom decreased motivation to initiate and perform purposeful self-directed activities.

As used herein, the term "brain injury disorder" refers to a lesion in the brain that occurs after birth and is not congenital, degenerative, or hereditary. The term encompasses traumatic brain injury, for example from a car accident or sports injury, and acquired brain injury, such as ischemic stroke, transient ischemic stroke, hemorrhagic stroke, brain tumor, meningitis, or encephalitis.

In preferred embodiments of the fifth aspect of the present invention, the psychiatric or neurological disorder is selected from (i) an obsessive-compulsive disorder, (ii) a depressive disorder, (iii) an anxiety disorder, (iv) substance abuse, ( v) an avolition disorder, and (vi) a brain injury disorder.

According to particular embodiments of the fifth aspect of the present invention, the depressive disorder is a major depressive disorder. According to even more particular modalities, major depressive disorder is treatment-resistant major depressive disorder.

Compositions comprising the deuterated N,N-dimethyltryptamine compounds of the present invention can be synthesized on a gram scale up to a multi-kg scale by following the reaction scheme (synthetic scheme) provided in Scheme 1.

A particular advantage of the present invention, in particular but not limited to the compounds obtainable according to its second aspect and the method of its sixth aspect, is that the described reductions according to these aspects of the invention allow particularly purities. obtained, without the need for subsequent chromatographic purification (for example, column chromatography), thus increasing the efficiency through which the compounds of the invention can be prepared. Additionally, the ability to avoid the use of chromatography to achieve high purities makes scale-up more effective and therefore cost-effective. Identification of the compositions obtained by the methods of the present invention can be achieved, if desired, by chromatographic separation of the components of the mixtures by conventional means available to those skilled in the art in combination with spectroscopic and/or mass spectrometric analysis.

The compositions described above can be further modified by adding one or more deuterated N,N-dimethyltryptamine compounds. Stocks of such deuterated N,N-dimethyltryptamine compounds can be obtained, for example, from the chromatographic separation described above. In this way, for example, the compounds of the seventh aspect of the invention can be obtained.

Although the identification of the compositions resulting from the reduction described in the present description can be achieved by means of chromatographic separation of the components of the mixtures, in combination with spectroscopic and/or spectrometric analysis of masses, a particular benefit of the present invention is that, according to particular modalities, there may be no need to do so. This is because, beyond the purities achievable according to the present invention, we have recognized, as mentioned above, that there is a quantifiable relationship between the degree of deuteration (or in other words, the amount or ratio of deuterium in the N,N-dimethyltryptamine compounds in the compositions of the present invention) and the metabolic half-life of the resulting composition. The degree of deuteration can be controlled through the amount of deuterium-containing reducing agent used in the method of the invention, through which (according to particular modalities) the compositions of the invention can be obtained and therefore , control can be exerted in a predictable manner, overpotentiation of the metabolic half-life of the parent compound (undeuterated N,N—dimethyltryptamine).

In particular, as detailed in Reference Example 1 and related Figures 2 and 3, the inventors have shown that increasing deuterium enrichment at the a-carbon of N,N-dimethyltryptamine increases metabolic stability, leading to decreased clearance and longer half-life, where there is a linear relationship between molecular weight and half-life between 188.3 and 190.3 grams per mole, and synergistic primary and secondary kinetic isotope effects provide a relationship predictable between molecular weight and half-life for compounds and compositions of formula I where R 1 is H between 188.3 and 196.3 grams per mole.

As used herein, average molecular weight means the weight average of the molecular weights of the N,N-dimethyltryptamine compounds, the a-prothio,a-deutero-N,N-dimethyltryptamine compounds, and the a, a-dideutero-N,N-dimethyltryptamine, as measured by a suitable mass spectroscopic technique, eg LC-MS SIM (selected ion control), ignoring any contribution to weight from pharmaceutically acceptable salt formation, where appropriate.

It is to be understood that compositions with such specific average molecular weights can be achieved by those skilled in the art through the teachings herein, in particular by adjusting the relative ratios of dimethylamine:deuterated dimethylamine used in step 1 by varying the deuteration level. at the N,N—dimethyl position.

The methods by which the compounds of formula I can be produced are described below and are suitable for the production of compounds of formula I of high purity. In some embodiments, the compound of formula I, or a pharmaceutically acceptable salt thereof, is between 99% and 100% pure by HPLC, such as between 99.5% and 100% pure by HPLC. In some embodiments, the compound of formula I, or a pharmaceutically acceptable salt thereof, is between 99.9% and 100% pure by HPLC, such as between 99.95% and 100% pure. by HPLC.

In some embodiments, the compound of formula I, or a pharmaceutically acceptable salt thereof, produces two or fewer impurity peaks by HPLC. In some embodiments, when the compound of formula I, or a pharmaceutically acceptable salt thereof, produces impurity peaks by HPLC, no impurity peak exceeds 0.2%. In some embodiments, no HPLC impurity peak is greater than 0.1%.

In some embodiments, the compound of formula I is in the form of a pharmaceutically acceptable salt. The pharmaceutically acceptable salt often comprises a compound of formula I and a suitable acid. The compound of formula I is typically protonated at -N(R2R3)2, forming —[NHR2R3]+, and the resulting positive charge is counteracted by an anion.

P. H. Stahl and C. G. Wermuth provide an overview of pharmaceutical salts and the acids they contain in the Handbook of Pharmaceutical Salts: Properties, Selection and Use, Weinheim/Zürich: Wiley—VCH/VHCA, 2002. The acids described in this review are suitable components of the pharmaceutically acceptable salt of formula I.

In some embodiments, the acid is any one selected from the group consisting of fumaric acid, tartaric acid, citric acid, hydrochloric acid, acetic acid, lactic acid, gluconic acid, 1-hydroxy-2-naphthoic acid, 2,2- Dichloroacetic, 2-hydroxyethanesulfonic acid, 2-oxoglutaric acid, 4-acetamidobenzoic acid, 4-aminosalicylic acid, adipic acid, ascorbic acid, aspartic acid, benzenesulfonic acid, benzoic acid, camphoric acid, camphor-10-sulfonic acid, decanoic acid, hexanoic acid, octanoic acid, carbonic acid, cinnamic acid, cyclamic acid, dodecylsulfuric acid, ethane-1,2-disulfonic acid, ethanesulfonic acid, formic acid, galactaric acid, gentisic acid, glucoheptonic acid, glucuronic acid, glutamic acid, glutaric acid , glycerophosphoric acid, glycolic acid, hippuric acid, hydrobromic acid, isobutyric acid, lactobionic acid, lauric acid, maleic acid, malic acid, malonic acid, mandelic acid, m acid ethanesulfonic acid, naphthalene-1,5-disulfonic acid, naphthalene-2-sulfonic acid, nicotinic acid, nitric acid, oleic acid, oxalic acid, palmitic acid, pamoic acid, phosphoric acid, proprionic acid, pyroglutamic acid (—L), acid salicylic, sebacic acid, stearic acid, succinic acid, sulfuric acid, thiocyanic acid, toluenesulfonic acid and undecylenic acid.

Often the acid is any one selected from fumaric acid, tartaric acid, citric acid and hydrochloric acid. In some embodiments, the acid is fumaric acid, ie, the pharmaceutically acceptable salt is a fumarate salt.

Also described herein is a synthetic method for preparing a compound of formula I or a pharmaceutically acceptable salt thereof. The method comprises step 2 and optionally step 1, wherein step 1 comprises:

(i) reacting a compound of formula III with two or more coupling agents to produce an activated compound;

(ii) reacting the activated compound with an amine having the formula (R2)2NH to produce a compound of formula II;

and wherein step 2 comprises reacting the compound of formula II with LiAID4,

where:

R1 is selected from H and D;

R2 is CD3;

R3 is selected from CH3 and CD3;

both andH are D.

For the avoidance of doubt, the modalities relating to the compound of formula I, or a pharmaceutically acceptable salt thereof, also apply, of the first aspect of the invention also applies mutatis mutandis to the compound of formula I (and thus compounds of formulas III and II) of the synthetic method.

The synthetic method avoids the use of the troublesome oxalyl chloride and employs compounds of formula III, which can be derived from auxin derivatives. Auxins of formula III of high quality and purity are commercially available at scale and/or can be readily synthesized via the Fischer synthesis, the Bartoli synthesis, the Japp-Klingemann synthesis or the Larock synthesis (see, for example , M. B. Smith and J. March, 2020, March's Advanced Organic Chemistry, 8th Edition, Wiley, New Jersey). The method is efficient, scalable, compliant with Current Good Manufacturing Practices (cGMP) and is suitable for the production of high purity compounds of formula I. For example, the method is suitable for the production of compounds of formula I on batch scales ranging from 1 g to 100 kg and is suitable for the production of compounds of formula I with a purity >99.9% and an overall yield of 65% or more.

The compound of formula II is produced by reacting a compound of formula III with two or more coupling agents to produce an activated compound, and by reacting the activated compound with an amine. which has the formula R2R3NH. Without wishing to be limited by theory, it is understood that the nitrogen atom of the amine is attached to the carbonyl carbon atom of formula III, resulting in the formation of the compound of formula II. For the avoidance of doubt, the R2 and R3 groups of formulas II and I are derived from the R2 and R3 groups of the amine. Thus, as described above, R2 of formulas II and I is CD3, and R3 of formulas II and I is independently selected from CH3 and CD3.

The compound of formula I is produced by reacting the compound of formula II with LiAlD4. Without intending to be bound by theory, it is understood that the deuteride ions provided by LiAlD4 bind to the carbonyl carbon atom of formula II, resulting in the formation of the compound of formula I. For the avoidance of doubt, the yH groups of formula I are they derive from the deuteride ions provided by LiAlD4.

As described above, the method comprises stage 1 and stage 2. Stage 1 comprises:

(i) reacting a compound of formula III with two or more coupling agents to produce an activated compound; Y

(ii) reacting the activated compound with an amine having the formula R2R3NH to produce a compound of formula II.

The term "coupling agent" refers to an agent that facilitates the chemical reaction between an amine and a carboxylic acid. The two or more coupling agents may comprise a carboxylic acid activating agent, i.e., an agent that reacts with the carboxylic acid moiety of formula III to produce a compound comprising an activated moiety derived from the original carboxylic acid moiety that is more likely to react with an amine than with the parent carboxylic acid moiety.

The activated compound is the product of the reaction between the compound of formula III and the two or more coupling agents. When the two or more coupling agents comprise carboxylic acid activating agents, the activated compound comprises an activated moiety, derived from the parent carboxylic acid moiety of formula III, which is more likely to react with an amine than the parent carboxylic acid moiety. .

The two or more coupling agents may comprise a carboxylic acid activating agent. The two or more coupling agents may comprise an additive coupling agent.

An additive coupling agent (also referred to herein as "additive") is an agent that improves the reactivity of a coupling agent. The additive may be a compound capable of reacting with the reaction product of formula III and the coupling agent (the product being a compound comprising an activated moiety) to produce a compound comprising a further activated moiety that is more likely that reacts with an amine than the original activated moiety.

The additive may be capable of reacting with the reaction product of formula III and the coupling agent (the product being a compound comprising an activated moiety) to produce an activated compound comprising a further activated moiety that is more likely to react with an amine than the original activated moiety.

Often the two or more coupling agents comprise a carboxylic acid activating agent and an additive coupling agent.

At least one of the two or more coupling agents may be selected from the group consisting of carbodiimide coupling agents, phosphonium coupling agents, and 3-(diethoxy-phosphoryloxy)-1,2,3-benzo[d]triazin- 4(3H)—one (DEPBT), such as a carbodiimide coupling agent or a phosphonium coupling agent. At least one of the two or more coupling agents may be a carbodiimide coupling agent.

A carbodiimide coupling agent is a coupling agent comprising a carbodiimide group R'-N=C=NR", where R' and R" are hydrocarbyl groups optionally substituted with heteroatoms selected from nitrogen, sulfur and oxygen, typically nitrogen. . Often, R' and R" are independently selected from C1-C6alkyl, C5-C6cycloalkyl, CrCaalkylamino, and morpholinoC1-C6alkyl. Often, CrCaalkyl is C3alkyl, C5-C6cycloalkyl is cyclohexyl, CrCaalkylamino is dimethylaminopropyl, and/or morpholinoC1-C6alkyl is morpholinoethyl The carbodiimide coupling agent can be any one selected from the group consisting of dicyclohexylcarbodiimide (DCC), diisopropylcarbodiimide (DIC), (N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide (EDC), and 1-cyclohexyl-( 2-morpholinoethyl)carbodiimide metho-p-toluene sulfonate (CMCT).The carbodiimide coupling agent can be any one selected from the group consisting of dicyclohexylcarbodiimide (DCC), diisopropylcarbodiimide (DIC) and (N-(3-dimethylaminopropyl)- N'-ethylcarbodiimide (EDC) Often the carbodiimide coupling agent is N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide (EDC), typically as a hydrochloride salt (EDC.HCI) EDC or EDC. HCI are particularly pr effered since they are not toxic and are highly soluble in water, which facilitates their practically complete removal in the treatment and washing stages of stage 1.

A phosphonium coupling agent comprises a phosphonium cation and a counterion, typically a hexafluorophosphate anion. The phosphonium cation may be of the formula [PRa3Rb]+ where Ra is di(C1-C6)alkylamino or pyrrolidinyl and Rb is halo or a hydrocarbyl group optionally substituted with nitrogen and/or oxygen atoms. Often Rb is bromo, benzotriazol-1-yloxy, or 7-aza-benzotriazol-1-yloxy.

The phosphonium coupling agent can be any one selected from the group consisting of benzotriazol-1-yloxy-tris(dimethylamino)-phosphonium hexafluorophosphate (BOP), bromo-tripyrrolidino-phosphonium hexafluorophosphate (PyBrOP), benzotriazol-1-yloxy-tripyrrolidino -phosphonium hexafluorophosphate (PyBOP), tripyrrolidinophosphonium 7-aza-benzotriazol-1-yloxy-hexafluorophosphate (PyAOP), and ethyl cyano(hydroxyimino)acetate—O2) tri-(1-pyrrolidinyl)-phosphonium hexafluorophosphate (PyOxim).

At least one of the two or more coupling agents may be an additive coupling agent selected from the group consisting of 1-hydroxybenzotriazole (HOBt), hydroxy-3,4-dihydro-4-oxo-1,2,3-benzotriazine (HOOBt ), N-hydroxysuccinimide (HOSu), 1-hydroxy-7-azabenzotriazole (HOAt), ethyl 2-cyano-2-(hydroxymino)acetate (Oxyma Pure), 4-(N,N-dimethylamino)pyridine ( DMAP), N-hydroxy-5-norbornene-2,3-dicarboximide (HONB), 6-chloro-1-hydroxybenzotriazole (6-Cl-HOBt), 3-hydroxy-4-oxo-3,4-dihydro-1 ,2,3-benzotriazine (HODhbt), 3-hydroxy-4-oxo-3,4-dihydro-5-azabenzo-1,2,3-triazene (HODhat), and 3-hydroxyl-4-oxo-3,4 —dihydro— 5-azepine benzo-1,3-diazines (HODhad).

At least one of the two or more coupling agents may be an additive coupling agent selected from the group consisting of 1-hydroxybenzotriazole (HOBt), hydroxy-3,4-dihydro-4-oxo-1,2,3-benzotriazine (HOOBt ), N-hydroxysuccinimide (HOSu), 1-hydroxy-7-azabenzotriazole (HOAt), ethyl 2-cyano-2-(hydroxymino)acetate (Oxyma Pure), and 4-(N,N-dimethylamino)pyridine ( DMAP).

At least one of the two or more coupling agents may be an additive coupling agent that is 1-hydroxybenzotriazole.

The two or more coupling agents may consist of a coupling agent and an additive coupling agent, wherein the coupling agent and the additive coupling agent may be as described in the above embodiments.

A benefit of using both a coupling agent and an additive coupling agent is an increased rate of formation of compounds of formula II from compounds of formula III and an amine having the formula R2R3NH. Furthermore, when an additive coupling agent is used together with a carbodiimide coupling agent, the likelihood of unwanted side reactions can be reduced. For example, reaction of a compound of formula III with a carbodiimide coupling reagent is likely to form an O-acylisourea. This can undergo rearrangement to form an N-acylurea, which is a stable compound that is unlikely to react with an amine. Additive coupling reagents can react with O-acylureas prior to rearrangement to N-acylureas and produce compounds that continue to react with an amine, instead of inactive N-acylureas.

Therefore, the two or more coupling agents may consist of a carbodiimide coupling agent and an additive coupling agent.

The two or more coupling agents may consist of N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide (EDC), typically as a hydrochloride salt (EDC.HCI) and 1-hydroxybenzotriazole (HOBt).

Often an excess of coupling agent is used relative to the compound of formula III. The ratio of coupling agent: compound of formula III can be from about 1:1 to about 3:1, typically from about 1:1 to about 2:1, and more typically from about 1:1 to about 1.5:1. .

Often an excess of additive coupling agent is used relative to the compound of formula III. Sometimes the ratio of additive coupling agent: compound of formula III is from about 1:1 to about 3:1, typically from about 1:1 to about 2:1, and more typically from about 1:1 to about 1.5 :1.

When the two or more coupling agents comprise a coupling agent and an additive coupling agent, a ratio of coupling agent: compound of formula III and additive coupling agent: compound of formula III of about 1:1 to about 1 may be used. .5:1.

As described above, step 1 comprises reacting the activated compound (the product of reacting a compound of formula III with two or more coupling agents) with an amine having the formula R2R3NH to produce a compound of formula II. R2 of formulas II and I is CD3 and R3 of formulas II and I is independently selected from CH3 and CD3.

The ratio of amine: compound of formula III used in the method is often about >1:1. Sometimes the ratio of amine: compound of formula III is from about 1:1 to about 3:1, typically from about 1:1 to about 2:1.

Sometimes, step 1 further comprises isolating the compound of formula II. Techniques in the art suitable for the isolation of a compound of formula II are known to those skilled in the art. For example, a compound of formula II can be extracted into an organic solvent such as dichloromethane or ethyl acetate, washed with an aqueous solution such as a basic aqueous solution, and concentrated. To increase purity, the isolated compound of formula II can be recrystallized. The person skilled in the art knows techniques that are suitable for the recrystallization of compounds of formula II. For example, the compound of formula II can be dissolved in the minimum amount of solvent at a given temperature (for example, at room temperature (for example, 15 to 25 °C) or at elevated temperatures when heat is applied to the solution). and the resulting solution cooled to favor precipitation. Alternatively, or in addition, the volume of the solution can be reduced to favor precipitation, for example, by simple evaporation at ambient temperature and pressure. Alternatively, or in addition, an antisolvent (in which the compound of formula II is less soluble than the solvent already present) may be used.

The isolated compounds of formula II are stable and can be stored as solids at room temperature, eg, about 20°C, in air. They can, but need not, be stored under inert conditions, eg under nitrogen or argon, or at reduced temperatures, eg in a refrigerator or freezer. Typically, steps (i) and (ii) of step 1 are carried out in a suitable solvent. The person skilled in the art can assess which solvents are suitable for these steps. Examples of suitable solvents include dichloromethane (DCM), acetone, isopropyl alcohol (IPA), isopropyl acetate (iPrOAc), tert-butyl methyl ether (TBME), 2-methyltetrahydrofuran (2-MeTHF), and ethyl acetate (EtOAc). In some embodiments, steps (i) and (ii) of step 1 are carried out in dichloromethane.

Steps (i) and (ii) of step 1 are carried out at a suitable temperature and the person skilled in the art can assess which temperatures are suitable for these steps. Often, steps (i) and (ii) of step 1 are carried out at temperatures from about 10°C to about 30°C. In some embodiments, steps (i) and (ii) of step 1 are carried out at room temperature (about 20°C).

Sometimes stage 1 of the method comprises the steps of:

(1) contacting a compound of formula III and between 1 and 1.5 equivalents of an additive coupling agent and between 1 and 1.5 equivalents of a carbodiimide coupling agent to produce a first composition; Y

(2) contacting the first composition with between 1 and 2 equivalents of an amine having the formula R2R3NH to produce a second composition.

Often, 1 g or more, such as 1 g to 100 kg or 1 g to 1 kg of a compound of formula III, is employed in the method. The contact of the stages i. and ii. it is often carried out in the presence of a first solvent, such as between 5 and 20 volumes of a first solvent. The first solvent can be selected from any of dichloromethane (DCM), acetone, isopropyl alcohol (IPA), isopropyl acetate (iPrOAc), tert-butyl methyl ether (TBME), 2-methyltetrahydrofuran (2-MeTHF), and ethyl acetate (EtOAc). ). Typically the first solvent is DCM.

Often stage i. further comprising stirring or agitating the first composition. The first composition can be stirred for at least 30 minutes, such as 30 minutes to 3 hours or 30 minutes to 2 hours, preferably at least 1 hour, for example 1 to 3 hours or 1 to 2 hours. The first composition can be kept at a temperature between 10°C and 30°C.

The amine of step ii. it is often dissolved in a solvent, such as tetrahydrofuran (THF) or ether, prior to contact. The amine may be present in the solvent at a concentration of about 2 M. Typically, the amine from step ii. dissolves in THF.

Sometimes stage ii. further comprising stirring or agitating the second composition. The second composition can be stirred for at least 30 minutes, such as 30 minutes to 3 hours or 30 minutes to 2 hours, preferably at least 1 hour, for example 1 to 3 hours or 1 to 2 hours. The second composition can be kept at a temperature between 10°C and 30°C.

Stages ii. may further comprise contacting the second composition with a basic aqueous solution to produce a third composition, for example contacting the second composition with between 2 and 10 volumes of a basic aqueous solution such as an aqueous solution comprising potassium carbonate .

Sometimes stage ii. further comprising stirring or agitating the third composition. The third composition can be stirred for at least 1 minute, such as 1 to 15 minutes or 1 to 10 minutes, preferably at least 5 minutes, for example 5 to 15 minutes or 5 to 10 minutes. The third composition can be kept at a temperature between 10°C and 30°C.

When the third composition comprises an organic and an aqueous component, stage ii. it may further comprise separating the organic component from the aqueous component. The organic component can be separated from the aqueous component within 8 hours after the contact of step i.

Sometimes stage 1 of the method comprises the steps of:

Yo. add to a first container 1 g or more of a compound of formula III and between 1 and 1.5 equivalents of an additive coupling agent,

ii. add to the first vessel between 5 and 20 volumes of a first solvent selected from DCM, acetone, IPA, iPrOAc, TBME, 2-MeTHF, and EtOAc,

iii. add to the first container between 1 and 1.5 equivalents of a carbodiimide coupling agent, iv. Shake the contents of the first container for at least 30 minutes, preferably at least 1 hour (for example, 1 to 2 hours), between 10 °C and 30 °C,

v. add to the first container between 1 and 2 equivalents of an amine having the formula R2R3NH, where the amine is preferably dissolved in an ether solvent,

saw. further agitate the contents of the first container for at least 30 minutes, preferably at least 1 hour (for example, 1 to 2 hours), between 10 °C and 30 °C,

vii. add to the first container between 2 and 10 volumes of a basic aqueous solution,

viii. further agitate the contents of the first container for at least 1 minute, preferably at least 5 minutes (e.g. 5 to 10 minutes), between 10°C and 30°C,

ix. allowing an immiscible organic fraction to separate from an aqueous fraction, wherein the organic fraction comprises the compound of formula II, and

x. removing the organic fraction comprising the compound of formula II,

where stages i. to x. are carried out in a single 8-hour period.

Often the first solvent is DCM.

The amine can be dissolved in THF, for example, at a concentration of 2 M. Often the basic aqueous solution comprises potassium carbonate.

Sometimes stage 1 of the method further comprises the steps of:

xi. drying the organic fraction with a drying agent, for example, a drying agent selected from calcium chloride, magnesium sulfate and sodium sulfate,

xiii. filter the organic fraction,

xiii. concentrating the organic fraction, for example under vacuum such as at a pressure of less than 1 atmosphere, xiv. add the concentrated organic fraction to a second container,

xv. adding 2 to 10 volumes of a second solvent to the second vessel, where the second solvent is selected from IpA, EtOAc, IPrOAc, acetonitrile (MeCN), TBME, THF, 2-MeTHF, and toluene,

xvi. Shake the contents of the second container for at least 1 hour, preferably at least 2 hours (for example, 2 to 3 hours), at temperatures between 45°C and 55°C,

xvii. cool the contents of the second container to temperatures between 15 °C and 25 °C,

xviii. filtering the contents of the second container to obtain a filtrate, wherein the filtrate comprises the compound of formula II, and

xix. dry the filtrate.

The drying agent of step xi. it is typically magnesium sulfate. Often the solvent of step xv. it is selected from TBME and IPA.

Step 2 of the method comprises reacting the compound of formula II with LiAlD4 to produce a compound of formula I. LiAlD4 can be reacted with the compound of formula II.

The amount of LiAlD4 used relative to the compound of formula II is often <1:1. For the avoidance of doubt, the ratios of LiAlD4 relative to compound of formula II refers to the total amount of LiAlD4 used relative to the amount of compound II. Sometimes the ratio of LiAlD4:compound of formula II is 0.5:1 to 1:1, such as 0.8:1 to 1:1. Typically, the ratio of LiAlD4:compound of formula II is 0.9:1.

Typically, step 2 of the method is carried out in a suitable solvent. The person skilled in the art can assess which solvents are suitable for step 2. Examples of suitable solvents include ethers such as THF and diethyl ether. Often stage 2 is carried out in THF.

Often the LÍAID4 is provided as a solution or suspension of LÍAID4 in a suitable solvent such as an ether, for example THF or diethyl ether, typically THF.

Step 2 of the method is carried out at a suitable temperature and the person skilled in the art can assess which temperatures are suitable for these steps. Often, stage 2 is carried out at temperatures from about -5°C to about 65°C.

Generally, step 2 further comprises isolating the compound of formula I. Techniques in the art are known to those skilled in the art suitable for the isolation of a compound of formula I. For example, by stopping the reaction (for example, with a aqueous solution of a tartrate salt such as the Rochelle salts), a compound of formula I can be extracted into an organic solvent such as an ether, eg THF or diethyl ether, washed with an aqueous solution such as a basic solution aqueous and concentrate. The isolated compound of formula I can be recrystallized. Techniques that are suitable for the recrystallization of a compound of formula I are known to those skilled in the art. The examples of recrystallization techniques described with respect to the recrystallization of a compound of formula II apply mutatis mutandis to the recrystallization of a compound of formula I.

Often, about 1 g or more is employed in the method, such as about 1 g to about 100 kg or about 1 g to about 1 kg of a compound of formula II.

Typically, step 2 of the method comprises contacting a compound of formula II and between about 0.8 and about 1 equivalent, such as about 0.9 equivalents of LiAlD4 to produce a first composition.

The contacting is typically carried out in the presence of a solvent such as an ether, eg THF or diethyl ether, usually THF.

Often the contact comprises the dropwise addition of LiAlD4 to a compound of formula II, wherein LiAlD4 is provided as a solution or suspension of LiAlD4 in a suitable solvent, such as an ether, eg THF or diethyl ether. The LiAlD4 can be provided as a solution or suspension of 2.4 M or 2 M LiAlD4 in THF. Sometimes the LiAlD4 is provided as a 2M LiAlD4 solution or suspension or in THF.

Contact is often carried out at temperatures from about -5°C to about 65°C.

Often step 2 further comprises stirring or agitating the first composition. The first composition can be stirred or agitated for about 1 hour to about 6 hours, typically about 2 hours. The first composition can be stirred or agitated at a temperature of about 55°C to about 65°C. Often the first composition is stirred or agitated at a temperature of about 55°C to about 65°C and then cooled to temperatures of about 10°C to about 30°C.

Typically, the compound of formula II is contacted with approximately 0.9 equivalents of LiAlD4. Step 2 of the method of the invention may comprise the steps of:

Yo. adding to a third container 1 g or more (eg, 1 g to 1 kg) of a compound of formula II, ii. add to the third container between 5 and 20 volumes of an ether solvent,

iii. add to the third vessel, dropwise over at least 15 minutes (for example, 15 to 30 minutes), a solution of 0.8 to 1 equivalent of LiAlD4 in the ether solvent at a temperature between -5 °C and 65°C,

iv. shake the contents of the third container between 55 °C and 65 °C between 1 hour and 6 hours, preferably 2 hours, and v. cool the content of the third container between 10 °C and 30 °C,

wherein the content of the third container comprises a compound of formula I.

Often the ether solvent is THF. Typically, 0.9 equivalents of LiAlD4 is added to the third container in step iii. The LiAlD4 is typically added to the third vessel as a 2.4 M or 2 M solution in THF. Sometimes the LiAlD4 is added to the third vessel as a 2 M solution in THF.

Sometimes stage 2 of the method comprises work that comprises the stages of:

saw. add between 5 and 20 volumes of an aqueous solution of a tartrate salt (such as Rochelle salts) to a fourth container,

vii. add a composition comprising the crude compound of formula I, for at least 15 minutes (such as 15 minutes to 1 hour), preferably at least 30 minutes (such as 30 minutes to 1 hour), to the fourth container at between 15 °C and 25 °C, and

viii. Shake the contents of the fourth container at 15°C to 25°C for at least 30 minutes (eg, 30 minutes to 1 hour).

For the avoidance of doubt, the composition comprising the crude compound of formula I refers to the contents of the third container upon completion of step v. of step 2, described above.

Step 2 of the method may further comprise the steps of:

ix. allowing an organic fraction to separate from an aqueous fraction, wherein the organic fraction comprises the compound of formula I,

x. withdraw the aqueous fraction from the fourth container,

xi. add between 5 and 20 volumes of a brine solution to the fourth container,

xiii. shake the contents of the fourth container at a temperature between 15 °C and 25 °C for at least 5 minutes (for example, 5 to 15 minutes),

xiii. removing the organic fraction comprising the compound of formula I as free base,

xv. drying the organic fraction by using a drying agent, such as a drying agent selected from calcium chloride, magnesium sulfate and sodium sulfate,

xv. filter the organic fraction, and

xvi. concentrating the organic fraction, for example under vacuum such as at a pressure of less than 1 atmosphere.

The isolated compounds of formula I (produced via step 2) are stable and can be stored as solids at room temperature, eg, about 20°C, in air. They may, but need not, be stored under inert conditions, eg under nitrogen or argon, or at reduced temperatures, eg in a refrigerator or freezer. Sometimes the compound of formula I is stored in a solvent, for example dissolved in ethanol. Sometimes the compound of formula I is stored in a solvent for more than 8 hours, typically more than 12 hours.

As described above, the compound of formula I may be in the form of a pharmaceutically acceptable salt. A pharmaceutically acceptable salt can be formed from a compound of formula I by reaction with a suitable acid. Thus, the method may further comprise a step 3, wherein the compound of formula I is reacted with an acidic reagent to produce a pharmaceutically acceptable salt of the compound of formula I. The acidic reagent may be suitable for crystallizing a pharmaceutically acceptable salt. acceptable form of the compound of formula I.

For the avoidance of doubt, when a reagent is expressed in the present description as a number of equivalents, this is with respect to the molar equivalents of the compound of formula III, formula II or formula I for the reagents in step 1, step 2 or step 3, respectively.

A method for synthesizing a compound of formula I, or a pharmaceutically acceptable salt thereof, often comprises step 1, step 2 and step 3, wherein step 1 comprises:

(i) reacting a compound of formula III with two or more coupling agents to produce an activated compound;

(ii) reacting the activated compound with an amine having the formula R2R3NH to produce a compound of formula II; Y

(iii) isolating the compound of formula II;

step 2 comprises reacting the compound of formula II with LiAlD4; Y

Step 3 comprises the step of reacting the compound of formula I with a suitable acid reagent to crystallize a pharmaceutically acceptable salt of the compound of formula I.

Sometimes, a ratio of acid reagent: formula I compound of 2:1:1 is used. Often the ratio of acid reagent: compound of formula I is 1:1.

Typically, step 3 of the method is carried out in a suitable solvent. One of skill in the art can assess which solvents are suitable for step 3. Examples of suitable solvents include ethanol, IPA, iPrOAc and MeCN. Stage 3 is often carried out in ethanol.

Step 3 of the method of the invention is carried out at a suitable temperature and the person skilled in the art can assess which temperatures are suitable for these steps.

Step 3 of the method often comprises contacting a compound of formula I and an acid reagent to produce a first composition. Often stage 3 contacting is carried out at temperatures of 70 to 100°C, for example 70 to 90°C or 70 to 80°C. Stage 3 contact is sometimes made at temperatures around 75°C.

Often, step 3 further comprises isolating the pharmaceutically acceptable salt of formula I. Techniques in the art suitable for the isolation of said compound are known to those skilled in the art. For example, when the compound is dissolved within a suspension, it can be separated from some of the other components of the suspension by filtration, such as hot filtration. The pharmaceutically acceptable salt of formula I can precipitate from the filtrate. The person skilled in the art knows methods to stimulate the precipitation of a compound from a solution, such as cooling the solution, concentrating the solution and/or adding a crystalline form of the compound to the solution to stimulate the nucleation and growth of more crystals. of the compound from the solution (ie seed). The pharmaceutically acceptable salt of formula I can be recrystallized. Techniques that are suitable for recrystallization of a pharmaceutically acceptable salt of formula I are known to those skilled in the art. The examples of recrystallization techniques described with respect to recrystallization of a compound of formula II apply mutatis mutandis to recrystallization of a pharmaceutically acceptable salt of formula I. Step 3 of the method may comprise the steps of:

Yo. adding to a fifth vessel at least one equivalent of a suitable acid reagent to crystallize a pharmaceutically acceptable salt of a compound of formula I,

ii. dissolving a compound of formula I as the free base in between 5 and 20 volumes of a solvent such as a solvent selected from ethanol, IPA, iPrOAc and MeCN and adding the solution to the fifth reaction vessel, iii. shake the contents of the fifth container at a temperature above 72 °C (such as, for example, 72 to 90 °C),

iv. filter the contents of the fifth container,

v. add the filtrate to a sixth container and cool the contents to a temperature of 67 °C to 73 °C, vi. optionally seeding the sixth container with a crystalline form of the pharmaceutically acceptable salt of the compound of formula I,

vii. Shake the contents of the sixth container at a temperature of 67 °C to 73 °C for at least 30 minutes (for example, 30 minutes to 1 hour),

viii. cool the contents of the sixth container to a temperature of -5 °C to 5 °C at a rate of 2 to 8 °C per hour, and

ix. filtering the contents of the sixth vessel to produce a filter cake comprising a pharmaceutically acceptable salt of the compound of formula I.

Often the solvent from step ii. it's ethanol. Often the cooling rate in stage viii. is 5°C per hour.

As described above, the pharmaceutically acceptable salt often comprises a compound of formula I and a suitable acid. The acids listed above as suitable components of the pharmaceutically acceptable salts of the invention apply mutatis mutandis to the acid reagents of step 3 of the method.

Often the acid reagent is any one selected from fumaric acid, tartaric acid, citric acid, and hydrochloric acid, such as fumaric acid.

The synthetic method described in the present disclosure is particularly useful for producing therapeutic deuterated dialkyl substituted tryptamines, since the method employs significantly less LiAlD4 than other syntheses known in the art, and since the method substitutes deuterium at the alpha position but not at the alpha position. beta position. LiAlD4 is one of the most expensive and difficult to manufacture reagents in this synthesis. In addition, the optimized methods described in the present description reduce the LiAlD4 requirements, for example from 2 equivalents to 0.9 equivalents, which increases the economic efficiency in the manufacture of deuterated compounds of formula I. In view of this, the compounds of formula I are cheaper to manufacture, via the synthetic method described herein, than the known deuterated analogues which are normally deuterated in both the alpha and beta positions.

The synthetic method described in the present description is efficient; the compounds of formula I can be produced in an overall yield of between 50% and 100%, such as between 60% and 100% or between 65% and 100%. The invention can be further understood with reference to the following non-limiting examples:

Reference Example 1

In the first example, the inventors demonstrate that the primary kinetic isotope effect conferred on N,N—dimethyltryptamine, when enriched with one or two deuterium at the alpha position, shows a linear relationship between average molecular weight and half-life. in human hepatocyte assays.

Use of Human Hepatocytes to Assess the In Vitro Intrinsic Clearance of Deuterated DMT Analog Mixtures Relative to DMT

In vitro intrinsic clearance determination is a valuable model for predicting hepatic clearance in vivo. The liver is the major organ of drug metabolism in the body, and contains both phase I and phase II drug-metabolizing enzymes, which are present in the intact cell.

The synthesis of the samples of

N,N—DMT 220.9 g (as free base) was prepared as N,N-DMT fumarate, using the chemistry depicted in Scheme 1. An additional 4—6 g of six partially deuterated mixtures were also produced by the use modified conditions.

Peso molecular: 188,27Mo ecuar weight: 175.18

Molecular weight: 188.27

Mo ecuar weight: 304.34 Scheme 1

DMT Reference Synthesis

Step 1: coupling of indole-3-acetic acid and dimethylamine

A 5 L vessel under N2 was charged with indole-3-acetic acid (257.0 g, 1.467 mol), hydroxybenzotriazole (HOBt, ~20% wet) (297.3 g, 1.760 mol), and dichloromethane (2313 mL) to give a milky white suspension. Next, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC.HCl, 337.5 g, 1.760 mol) was charged portionwise over 5 minutes at 16-22°C. The reaction mixture was stirred for 2 hours at room temperature before loading 2M dimethylamine in THF (1100 mL, 2200 mol) dropwise over 20 minutes at 20-30°C. The resulting solution was stirred at room temperature for 1 hour, where HPLC indicated 1.1% indole-3-acetic acid and 98.1% target product called step 1). The reaction mixture was then charged with 10% K2CO3 (1285 mL) and stirred for 5 minutes. The layers were separated, and the upper aqueous layer was extracted with dichloromethane (643 mL x 2). The organic extracts were combined and washed with saturated brine (643 mL). The organic extracts were then dried over MgSO4, filtered, and concentrated in vacuo at 45 °C. This provided 303.1 g of crude step 1 as an off-white sticky solid. The crude material was then slurried in tert-butylmethylether (TBME, 2570 mL) at 50 °C for 2 hours before cooling to room temperature, filtering, and washing with TBME (514 mL x 2). The filter cake was then dried in vacuo at 50 °C to give the step 1266.2 g (yield = 90%) as an off-white solid with a purity of 98.5% by H ^p L ^c and >95% by NMR.

Stage 2: DMT preparation

To a 5 L vessel under N2 was charged step 1 (272.5 g, 1.347 mol) and tetrahydrofuran (THF, 1363 mL) to give an off-white suspension. 2.4 M LiAlH4 in THF (505.3 mL, 1.213 mol) was then charged dropwise over 35 minutes at 20—56 °C to give an amber solution. The solution was heated at 60 °C for 2 hours where HPLC indicated stage 1 ND, target product group named stage 2, 92.5%, impurity 1 (2.6%), impurity 2 (1.9%) . The entire reaction mixture was cooled to room temperature and then charged to 25% Rochelle's salts solution (aq) (2725 mL) dropwise over 30 minutes at 20-30 °C. The resulting milky white suspension was allowed to stir at 20-25°C for 1 hour, after which the layers were separated and the upper organic layer was washed with saturated brine (681 mL). The organic layer was then dried over MgSO4, filtered, and concentrated in vacuo at 45 °C. The resulting crude oil was azeotroped with ethanol (545 mL x 2). This provided 234.6 g (yield = 92%) of step 2 with a purity of 95.0% by HPLC and >95% by NMR.

Step 3a (i)—(iii): preparation of DMT fumarate seed crystals

(i) Step 2 (100 mg) was taken up in 8 volumes of isopropyl acetate and heated to 50 °C before fumaric acid (1 equiv) was charged as a solution in ethanol. The flask was then allowed to mature at 50°C for 1 hour before cooling to room temperature and shaking overnight, resulting in a white suspension. The solids were isolated by filtration and dried for 4 hours at 50°C to provide 161 mg of product (>99% yield). The purity was determined by HPLC to be 99.5% and by NMR to be >95%.

(ii) Substituting isopropyl alcohol for isopropyl acetate in method (i) gave a white suspension after stirring overnight. The solids were isolated by filtration and dried for 4 hours at 50°C to provide 168 mg of product (>99% yield). The purity was determined by HPLC to be 99.8% and by NMR to be >95%.

Substitution of tetrahydrofuran for isopropyl acetate in method (i) gave a white suspension after stirring overnight. The solids were isolated by filtration and dried for 4 hours at 50°C to provide 161 mg of product (>99% yield). Purity was determined by HPLC to be 99.4% and by NMR to be >95%.

X-ray powder diffraction analysis showed that the products of each of methods 9i) to (iii) were the same, which were labeled as pattern A.

Step 3b: preparation of DMT fumarate

To a 5 L flanged flask under N2 was charged with fumaric acid (152.7 g, 1.315 mol) and step 2 (248.2 g, 1.315 mol) as a solution in ethanol (2928 mL). The mixture was heated to 75°C to give a dark brown solution. The solution was filtered into a 5 L jacketed flask previously heated (80 °C). The solution was then cooled to 70 °C and sown with pattern A (0.1 wt%), the seed was left to mature for 30 min before cooling to 0 °C at a rate of 5 °C/ time. After stirring for an additional 4 hours at 0 °C, the batch was filtered and washed with cold ethanol (496 mL x 2) and then dried at 50 °C overnight. This provided 312.4 g (yield = 78%) of step 3 with a purity of 99.9% by HPLC and >95% by NMR. ^x R ^p D: Pattern A.

Reference synthesis of deuterated mixtures of DMT compounds

A modified synthesis in step 2 using solid LiAlH4/LiAlD4 mixtures was adopted, using 1.8 equivalents of LiAlH4/LiAlD4 versus 0.9 equivalents using the process described above for undeuterated DMT.

Representative synthesis of a deuterated DMT (1:1 LiAlH4:LiAlD4) composition: A 250 mL 3-necked flask under N2 was charged with LiAlH4 (1.013 g, 26.7 mmol), LiAlD4 (1.120 g, 26.7 mmol ) and THF (100 mL). The resulting suspension was stirred for 30 minutes before loading step 1 (6 g, 29.666 mmol) in portions over 15 minutes at 20-40 °C. The reaction mixture was then heated at reflux (66 °C) for 2 hours, where HPLC indicated that no stage 1 remained. The mixture was cooled to 0 °C and quenched with 25% Rochelle salts (aq) ( 120 mL) for 30 minutes at <30 °C. The resulting slurry was stirred for 1 hour and then allowed to separate. The lower aqueous layer was removed and the upper organic layer was washed with saturated brine (30 mL). The organics were then dried over MgSO4, filtered, and concentrated in vacuo. This provided 4.3 g of crude material. The crude was then taken up in ethanol (52 mL) and charged with fumaric acid (2.66 g, 22.917 mmol) before heating to 75 °C. The resulting solution was allowed to cool to room temperature overnight before further cooling to 0-5°C for 1 hour. The solids were isolated by filtration and washed with cold ethanol (6.5 mL x 2). The filter cake was dried at 50 °C overnight to provide 5.7 g (yield = 63%) of product with a purity of 99.9% by HPLC and >95% by NMR.

Table 1

In vitro intrinsic clearance of deuterated DMT compounds and compositions

Intrinsic clearance of the human hepatocyte

Determination of intrinsic clearance in vitro (CLint) is a valuable model for predicting clearance in vivo. The liver contains both phase I and phase II drug-metabolizing enzymes, which are present in the intact cell and thus provides a valuable model for the study of drug metabolism. In particular, CLint in hepatocytes is a measure of a compound's potential to undergo metabolism and may be related to hepatic clearance in vivo also taking into account plasma protein binding and hepatic blood flow. Therefore, CLint can be used as an index of the relative metabolic stability of compounds and compared to other external probe substrates. Furthermore, measurement of CLint in vitro, where hepatic metabolic clearance is known to be a problem, may be a useful means of understanding the different pharmacokinetic behavior of compounds in vivo.

Testing method

Pooled human (mixed gender) hepatocytes from 10 donors were used to investigate the in vivo intrinsic clearance of analogs SPL026 and SL028 in three separate experiments:

• First experiment - human hepatocytes (mixed gender); 0.545 million cells/mL. Final organic concentration 1.05% consisting of 80.74% MeCN and 19.26% DMSO

• Second experiment: human hepatocytes (mixed gender); 0.427 million cells/mL. Final organic concentration 1% consisting of 84.7% MeCN and 15.3% DMSO.

• Third experiment: human hepatocytes (mixed gender); 0.362 million cells/mL CD-1 murine hepatocytes (male)

• Final organic concentration 1% consisting of 84.7% MeCN and 15.3% DMSO

test preparation

• Hepatocyte buffer is prepared as 6.2 mM NaHCO3, 9 mM Na HEPES, 2.2 mM D-Fructose, and DMEM in MilliQ water.

• Stock solutions of compounds and markers were made to 10 mM in DMSO and then diluted to 100 x assay concentration in 91:9 acetonitrile:DMSO.

• Hepatocytes were rapidly thawed in a 37°C water bath and once thawed decanted into hepatocyte buffer. Cells were spun down and the supernatant removed prior to counting and resuspension at final assay concentration.

test procedure

A concentration of 5 pM was used for all test compounds, as well as sumatriptan, serotonin, and benzylamine controls with 2 replicate incubations per compound in each experiment. This concentration was chosen to maximize the signal-to-noise ratio, while remaining below the Michaelis constant (Km) for the enzyme monoamine oxidase (MAO). Diltiazem and diclofenac controls were used at a laboratory validated concentration of 1 pM.

Hepatocytes were added to previously warmed (37 °C) incubation tubes. Next, previously prepared 100x stock solutions of test compounds were added to the incubation tubes and mixed thoroughly. Samples are taken at 7 time points (2, 4, 8, 15, 30, 45, and 60 minutes). At each time point, small aliquots were removed from the incubation and quenched 1:4 with ice-cold acidified methanol or internal standard containing acetonitrile.

The incubation tubes were orbitally shaken at 37 °C throughout the experiment.

Standard final incubation conditions are 1 pM compound in buffer containing nominally ~0.5 million viable cells/mL, ~0.9% (v/v) acetonitrile (MeCN) and ~0.1% (v/v) v) of DMSO (the specific test concentrations described above, section 2).

Warm samples are mixed thoroughly and the protein is precipitated at -20°C for a minimum of 12 hours. Then, the samples were centrifuged at 4 oC. Supernatants were transferred to a new 96-well plate for analysis.

Liquid chromatography-mass spectrometry (LC-MS/MS)

The following LC-MS/MS conditions were used for analysis:

Instrument: Thermo TSQ Quantiva with the Thermo Vanquish UPLC system Column: Luna Omega 2.1x50 mm 2.6pm

Solvent A: H2O 0.1% formic acid

Solvent B: Acetonitrile 0.1% formic acid

Flow rate: 0.8 mL/min

Injection volume: 1 pl

Column temp: 65 °C

Gradient:

MS parameters:

Positive ion spray voltage: 4000V

Vaporizer temperature: 450 °C

Ion Transfer Tube Temperature: 365°C

Envelope gas: 54

Auxiliary gas: 17

Sweep Gas: 1

Dwell time 8ms

MRM transitions:

• D0 = mass/charge ratio 189.136 > 144.179 (method determined from analysis of SPL026)

• D1 = mass/charge ratio 190.136 > 59.17 (method determined from analysis of SPL028ii)

• D2 = mass/charge ratio 191.137 > 60.169 (method determined from analysis of SPL028i)

• D6 = mass to charge ratio 195.17 > 64.127

• D8 = mass to charge ratio 197.2 > 146.17

MRM transitions were determined from a preliminary analysis of DMT samples that contained no deuterium (for the D0 transition) or had high levels of D1, D2, D6, or D8 deuteration (for the D1, D2, D6, and D6 transitions). D8, respectively).

The resulting concentration-time profile was then used to calculate intrinsic clearance (CLint) and half-life (t1^). To do this, the MS peak area or MS peak area/IS response for each analyte is plotted on a natural logarithmic scale on the y-axis versus sampling time (min) on the X-axis. this line is the elimination rate constant. This becomes a half-life times — In(2)/slope. Intrinsic clearance is calculated from the slope/elimination rate constant and the formula is CLint = (—1000*slope)/cell density in 1E6 cells/mL, to give units of microliter/min/million cells.

Clearance of six different mixtures of D2DMT analogues (SPL028i — SPL028vi) with and without MAO inhibitors The MAO contribution of six different a,a,-dideutero-N,N-dimethyltryptamine (D2DMT) compounds was examined using an inhibitor Combined irreversible MAO-A/B (100 nM clorgyline and 100 nM deprenyl/selegiline added as a cassette) by measuring intrinsic clearance in vitro using human hepatocytes (mixed gender) from 10 donors (0.545 million cells s /mL; final organic concentration 1.05% consisting of 80.74% MeCN and 19.26% DMSO).

effect of deuteration

Data were fitted with two separate linear models using linear regression analysis (one-way ANOVA), which revealed that deuterium enrichment at the a-carbon of DMT decreases intrinsic clearance linearly with increasing percentage D2 deuteration using the using the formula: y = D2 * — 6.04 12.9, r2=0.748 and molecular weight (MW) using the formula: y = MW * 79.5 98.8, r2=0.811.

96.6% of D2—DMT (SPL028i) experienced the greatest change in metabolic stability, a ~2-fold change in intrinsic clearance and half-life compared to SPL026 in initial hepatocyte studies (Table 3 and Table 4 ). The metabolic stability of the deuteration intermediates (SPL028ii—SPL028vi) increased in a manner that correlated with increasing deuteration level and molecular weight (Table 3 and Table 4).

Table 3 In vitro intrinsic clearance of SPL026 and 6 different mixtures of deuterated D2 analogs of SPL028 in human hepatocytes, highlighting the fold change in intrinsic clearance of SPL026 for each deuterated compound, with and without inhibitors. Compounds ordered by molecular weight.

Table 4 In vitro half-life of SPL026 and 6 different mixtures of deuterated D2 analogs of SPL028 in human hepatocytes, highlighting the fold change in intrinsic clearance of SPL026 for each deuterated compound, with and without inhibitors. Compounds ordered by molecular weight.

MAO contribution (see also figure 4)

Two-way ANOVA was performed to determine the influence of MAO inhibitors and compound deuteration on intrinsic clearance. There was a significant effect of MAO inhibitors on intrinsic clearance F(1, 6) = 11.42, p=0.0149, and deuteration on intrinsic clearance F(1, 6)=9.996, p=0.006.

The inclusion of MAO inhibitors was shown to have minimal effect on SPL026 (DMT) metabolism, resulting in ~4% slower intrinsic clearance (Table 5). MAO inhibitors were also shown to have a small effect on 96.6% of the deuterated D2 analogs (SPL028i) which underwent ~5% faster intrinsic clearance in the presence of MAO inhibitors (Table 5). These results indicate that MAO enzymes do not contribute significantly to the metabolism of SPL026 and SPL028i in human hepatic hepatocytes.

MAO inhibitors were shown to have a greater inhibitory effect on intrinsic clearance of the remaining five deuterated D2 analog mixtures (SPL028ii — SPL028vi). For these five compounds, showed that the inhibitory action of MAO inhibitors increases linearly with increasing deuteration level and molecular weight, with the exception of SPL028vi (Table 3). 49% of D2—deuterated SPL028iv had the largest change in intrinsic clearance (49%) with the inclusion of MAOIs (Table 5), while 36.8% of D2—deuterated SPL028iii saw the largest change ( ~2-fold) in metabolic stability relative to SPL026 in cell fractions with inhibitors (Tables 3 and 4).

These results indicate that increasing the level of deuteration at the a-carbon of DMT decreases the MAO enzyme metabolism of the compound.

*reference compound

Clearance of six reference D2DMT analog mixes (SPL028i — SPL028vi) and one reference D6—DMT analog mix (SPL028vii)

Reference synthesis of d6 —DMT: 028vii (Compound 5)

Stage 1

EDC.HCI (15.7 g, 81.90 mmol) was added to 3-indoleacetic acid (12.0 g, 68.50 mmol) and HOBt.H2O (1.16 g, 75.75 mmol) in DCM ( 108 mL) at room temperature. The reaction was stirred for 1 hour, after which N,N—diisopropylethylamine (DIPEA) (35.6 mL, 205.75 mmol) and d6-dimethylamine.HCl (9.0 g, 102.76 mmol) were added. (temperature maintained below 30 ° ^c ). The reaction was stirred for 1 hour at room temperature, after which HPLC analysis indicated 65.6 % product with 28.9 % 3-indoleacetic acid remaining. DIPEA (11.9 mL, 68.78 mmol) was added and the reaction stirred for 1 hour at room temperature. HPLC indicated no change in conversion. Aqueous potassium carbonate (6.0 g in 54 mL of water) was added and the phases were separated. The aqueous phase was extracted with DCM (2 x 30 mL). The combined organic extracts were washed with brine (2 * 30 mL), then aqueous citric acid (20% w/w, 50 mL), dried over MgSO4, and filtered. The filtrate was purified and the resulting solids were suspended in TBME (120 mL) and isolated by filtration. Purification by flash column chromatography gave 8.34 g of the desired product (58% yield). 1H NMR confirmed the identity of the product.

Stage 2

LiAlH4 (1 M in THF, 17.3 mL, 17.28 mmol) was added to a suspension from step 1 (4.0 g, 19.20 mmol) in THF (10 mL) at <30 °C. The resulting reaction was warmed to 60-65°C and stirred for 2 hours. HPLC analysis indicated complete consumption of stage 1 with 97.3% product formed. The reaction was cooled to room temperature and quenched in aqueous Rochelle's salts (10 g in 30 mL of water) at <30 °C. After stirring for 1 hour, the phases were separated. The aqueous phase was extracted with THF (20 mL). The combined organic extracts were washed with brine (20 mL), dried over MgSO4, filtered, and distilled (azeotroped with ethanol, 20 mL) to give the desired product as an amber oil (3.97 g). 1H NMR confirmed the identity of the product and indicated that 8.5% ethanol (without THF) was present giving an active yield of 3.63 g, 97%.

stage 3

The cfe-DMT free base (3.6 g active, 18.53 mmol) was dissolved in ethanol (43 mL) at room temperature. Fumaric acid (2.15 g, 18.53 mmol) was added and the solution was heated to 75 °C (solids crystallized during heating and did not redissolve). The resulting suspension was cooled to 0-5°C and stirred for 1 hour. The solids were isolated by filtration, washed with ethanol (2x7 mL) and dried. Further drying in a vacuum oven at 50°C yielded the desired d6—DMT fumaric acid salt (4.98 g, 87%).

Evaluation of degrees of deuteration

This was achieved using LCMS-SIM (SIM = single ion monitoring), the analysis provided a separate ion count for each mass of the three deuterated compounds of N,N-dimethyltryptamine (N,N—dimethyltryptamine (D0), a —protium, a-deutero-N,N-dimethyltryptamine (D1) and a,a-dideutero-N,N-dimethyltryptamine (D2)) at retention time for N,N-dimethyltryptamine. The percentage of each component was then calculated from these ion counts.

For example, %D0 = [D0/(D0 D1 D2)] * 100.

HPLC parameters

System: Agilent 1100/1200 Series Liquid Chromatograph or equivalent

Column: Phenyl triart; 150 * 4.6 mm, particle size 3.0 µm (Example:

YMC part number: TPH12S03—1546PTH)

Mobile Phase A: Water: Trifluoroacetic Acid (100:0.05%)

Mobile Phase B: Acetonitrile: Trifluoroacetic Acid (100:0.05%)

Gradient: Time % of A % of B

0 95 5

13 62 38

26 5 95

30.5 5 95

31 95 5 Flow rate: 1.0 mL/min

Stop Time: 31 minutes Post Run Time: 4 minutes Volume of 5 |jl Wash Bottle: N/A

injection:

Combined temperature 30 °C

column:

Wavelength: 200 nm, (4 nm) Reference: N/A Mass Spectrometry Parameters

System: Agilent 6100 series quadrupole LC—MS or equivalent

Drying gas flow: 12.0 l/min Temperature 350 °C

drying gas:

Nebulizer Pressure: 35 psig

Sliver: 110 Gain: 1.00

Compound RT RRT Conc. Diluent Detection Mass

D0 10.64 1.00 0.30 mg/mL CHaCN:H2O (50:50) (+) SIM 189.10 m/z D1 10.64 1.00 0.30 mg/mL CHaCN:H2O (50: 50) (+) SIM 190.10 m/z D2 10.64 1.00 0.30 mg/mL CHaCN:H2O (50:50) (+) SIM 191.10 m/z Interval MS-SIM is the mass target ± 0.1 m/z

Human hepatic in vitro intrinsic clearance of six different a,a,—dideutero— N,N -dimethyltryptamine (D2DMT) and one N,N—bis(trideutero—dimethyl)tryptamine (D6DMT, SPL028vii) compounds to investigate the effects of methyl group versus a-carbon deuteration on metabolic stability using human hepatocytes (mixed gender) from 10 donors (0.427 million cells/mL; 1% final organic concentration consisting of 84.7% of MeCN and 15.3% of D ^m S ^o ).

Table 6. In vitro intrinsic clearance and half-life of 6 different deuterated D2 DMT and D8DMT analog mixtures in human hepatocytes, sorted by increasing level of molecular weight

Data fitted with a linear regression model on the six different D2 deuterated compounds confirmed previous findings that deuterium enrichment at the a-carbon of DMT decreases intrinsic clearance linearly with increasing D2 deuteration level, y = D2* —8 .07 12.9, r2=0.690 and molecular weight. A linear regression model for molecular weight was also fitted using the formula: y = MW * 13.9 6.06, r2=0.923 revealing that molecular weight is a strong predictor of intrinsic clearance for the 6 different mixtures. deuterated D2 of SPL028.

Initial hepatocyte data did not suggest a relationship between molecular weight and intrinsic clearance of the D2—deuterated and D6—deuterated reference mixtures of SPL028, r2=0.0395.

Example 2

In the second example, the inventors detect a possible increase in half-life when N,N—dimethyltryptamine is deuterated at the N,N—dimethyl position.

Synthesis of d8 —DMT: 028viii (Compound 1)

For step 1 (coupling of 3—indoleacetic acid and d6—dimethylamine), see above

Stage 2

LiAlD4 (1 M in THF, 17.3 mL, 17.28 mmol) was added to a suspension from step 1 (4.0 g, 19.20 mmol) in THF (10 mL) at <30 °C. The resulting reaction was warmed to 60-65°C and stirred for 2 hours. HPLC analysis indicated complete consumption of stage 1 with 97.3% product formed. The reaction was cooled to room temperature and quenched in aqueous Rochelle's salts (10 g in 30 mL of water) at <30 °C. After stirring for 1 hour, the phases were separated. The aqueous phase was extracted with THF (20 mL). The combined organic extracts were washed with brine (20 mL), dried over MgSO4, filtered, and distilled (azeotroped with ethanol, 20 mL) to give the desired product as an amber oil (4.01 g). 1H NMR confirmed the identity of the product and indicated that 8.6% ethanol (without THF) was present giving an active yield of 3.66 g, 97%.

stage 3

The free base of compound 1 (3.6 g active, 18.53 mmol) was dissolved in ethanol (43 mL) at room temperature. Fumaric acid (2.15 g, 18.53 mmol) was added and the solution was heated to 75 °C (solids crystallized during heating and did not redissolve). The resulting suspension was cooled to 0-5°C and stirred for 1 hour. The solids were isolated by filtration, washed with ethanol (2x7 mL) and dried. Further drying in a vacuum oven at 50 °C gave the desired compound 1 as a fumaric acid salt (4.62 g, 81%).

Clearance of two D2DMT reference mixtures (SPL028i and SPL028ii), one D6DMT reference (SPL028vii, compound 5) and one D8—DMT analogue of the invention compound (SPL028viii, compound 1)

Further human hepatocyte assays were performed with two mixtures of SLP028 D2 deuterated analogs and two additional deuterated analogs: *D6DMT and D8DMT to measure intrinsic clearance in vitro using human hepatocytes (mixed gender) from 10 donors (0.362 million cells/mL).

Table 7. In vitro intrinsic clearance and half-life of two mixtures of different deuterated D2DMT, D6DMT and D8DMT analogues in human hepatocytes, sorted by increasing level of molecular weight

The possible presence of a secondary kinetic isotope effect was noted in the data; however, a linear regression model did not support a predictive relationship between molecular weight and intrinsic clearance for SPL026, SPL028i, SPL028ii, SPL029vii, and SPL028viii, r2=0.0445 in the human hepatocyte assay.

Example 3

In the third example, the inventors provide evidence that an additional protective effect is observed between the D2-deuterated SPL028i reference compound and a Da-deuterated SPL028viii compound of the invention (Compound 1). The data supports a synergistic effect on metabolic stability when deuterium is present in both the alpha and W,W-dimethyl positions of a compound of Formula I or any other compound or composition of any aspect of the present invention.

Using the liver mitochondrial fraction to model the human metabolism of deuterated DMT

Given the predicted 5-minute half-life of DMT in humans, the inventors expect that DMT will be extensively broken down before reaching the human liver. Therefore, an alternative non-tissue or organ specific in vitro assay was sought as a more appropriate system for modeling human DMT metabolism. Non-tissue or organ specific human metabolism analysis can be performed on human liver mitochondrial fractions.

The following assays performed on human liver mitochondrial fractions (tHLM) predict an improved fold change between SPL026 and reference compound D2—deuterated SPL028i compared to the fold change predicted in hepatocyte studies.

In vitro intrinsic clearance of the human mitochondrial fraction of SPL026 (DMT) with/without MAO—A and MAO—B inhibitors

For in vitro intrinsic clearance determination of *SPL026 with selective and irreversible MAO-A inhibitor (100 nM clorgyline) and MAO-B inhibitor (100 nM deprenyl/selegiline) added separately to 0.5 mg/mL fraction human liver mitochondrial. The MAO-A substrate, serotonin and the MAO-B substrate, benzylamine were added as positive controls confirming the presence of MAO-A and MAO-B and the action of the inhibitors clorgyline and deprenyl.

Table 8 Intrinsic clearance and half-life of SPL026 in the mitochondrial fraction of human liver

The half-life and intrinsic clearance of reference compound SPL026 were significantly increased with the MAO-A inhibitor (Chlorgiline), resulting in a 10-fold increase in intrinsic clearance compared to data for SPL026 without MAO inhibitors. Deprenyl (MAO-B inhibitor) did not show differences in human mitochondrial intrinsic clearance in relation to the fraction without inhibitors. These results suggest a role for MAO-A, but not MAO-B, in the metabolism of SPL026.

In vitro intrinsic clearance of the human mitochondrial fraction of reference compounds SPL026 (DMT), SPL028i (96.6% D2—DMT), SPL028iii (36.8% D2—DMT), SPL028vii (Compound 5), and a compound of the invention, SPL028viii (Compound 1)

For in vitro intrinsic clearance determination of *SPL026, *SPL028i, *SPL028iii and SPL028viii were added separately to 0.5 mg/mL human liver mitochondrial fraction. The MAO-A substrate 'serotonin' and the MAO-B substrate 'benzylamine' were added as positive controls and confirmed the presence of MAO-A and MAO-B. The experiment was repeated with the same substances and also with SPL028iii and SPL028vii.

Table 9 Intrinsic clearance and half-life of SPL026, SPL028i, SPL028ii, SPL028iii, SPL028vii and SPL028viii in the human liver mitochondrial fraction

The half-life increased with increasing deuteration level of the SPL028 compounds, compared to SPL026. Da—deuterate SPL028viii (Compound 1) had the greatest change in half-life (14-fold increase when both repeats were averaged) relative to SPL026. 96.6% of reference D2—deuterated SPL028i also showed a large change in half-life (10-fold increase when both repeats were averaged) compared to SPL026. 36.80% of reference D2—deuterated SPL028iii demonstrated a smaller change (3.6-fold increase) in clearance compared to SPL026. An independent Welch's t-test was performed for each deuterated compound compared to SPL026, the results are given in Table 10.

Table 10 t-test showing the significance of the half-life extension of SPL028 (i—viii)

conclusions

Complete deuteration at the alpha position of N,N—dimethyltryptamine increases metabolic stability 10-fold through the primary kinetic isotope effect in human mitochondrial fraction assays.

N,N—dimethyl deuteration potentially increases metabolic stability through secondary kinetic isotope effect in human hepatocyte assays.

More unexpectedly, the primary and secondary isotopic effects of deuteration at both the alpha position and the N,N—dimethyl position synergistically increase metabolic stability in compound 1, demonstrated with a 14-fold increase in metabolic stability in assays. human mitochondrial fraction.

Claims (15)

Yo. A deuterated NN-dimethyltryptamine compound of Formula (I) or a pharmaceutically acceptable salt thereof for use in therapy:

where: R1 is selected from H and D; R2 is CD3; R3 is selected from CH3 and CD3; Y both andH are D. 2. The deuterated NN-dimethyltryptamine compound for use according to claim 1, wherein: (i) R1 is H; I (ii) R3 is c D3. The deuterated NN-dimethyltryptamine compound for use according to claim 1 or claim 2, wherein the compound is in the form of a pharmaceutically acceptable salt, preferably wherein the pharmaceutically acceptable salt is a fumarate salt. 4. The deuterated NN-dimethyltryptamine compound for use of any preceding claim, wherein the compound is compound 1:

The deuterated NN-dimethyltryptamine compound for use of any one of claims 1 to 4, wherein: (i) the deuterated N,N-dimethyltryptamine compound has a longer half-life compared to undeuterated N,N-dimethyltryptamine in a human hepatocyte assay and/or (ii) The deuterated N,N-dimethyltryptamine compound has a longer half-life compared to undeuterated N,N-dimethyltryptamine in a mitochondrial fraction assay. 6. The deuterated NN-dimethyltryptamine compound for use of any of claims 1 to 3 and claim 5 when dependent on claims 1 to 3 wherein R1 is H. 7. The deuterated NN-dimethyltryptamine compound for use of any of claims 1 to 6 wherein R3 is CD3 and the compound has a molecular weight of 194.3 to 196.3 grams per mole. The deuterated NN-dimethyltryptamine compound for use of any of the preceding claims in the form of a pharmaceutical dosage form, preferably wherein the pharmaceutical dosage form is a parenteral dosage form or a solid dosage form. The deuterated NN-dimethyltryptamine compound for use according to claim 8, wherein the pharmaceutical dosage form comprises 0.001 mg to 100 mg in total of the deuterated N, N -dimethyltryptamine compound. The deuterated tyN -dimethyltryptamine compound of any of claims 1 to 9 for use in a method of treating a psychiatric or neurological disorder in a patient, preferably wherein the psychiatric or neurological disorder is selected from (i) an obsessive disorder compulsive disorder, (ii) a depressive disorder, (iii) a schizophrenia disorder, (iv) a schizotypal disorder, (v) an anxiety disorder, (vi) substance abuse disorder, (vii) an apathetic disorder, and (viii) a brain injury disorder; optionally, wherein the disorder is major depressive disorder or treatment resistant depression. A method for synthesizing a tyN-dimethyltryptamine deuterate compound of formula (I) as defined in any of claims 1 to 7:

or a pharmaceutically acceptable salt thereof, which comprises reacting a compound of formula (II) with LiAID4,

where R1 is selected from H and D, R2 is CD3; Y and R3 is selected from CH3 and CD3. The method of claim 11, wherein a ratio of LiAlD4:compound of formula (II) of from 0.8:1 to 2:1 is used. The method of claim 11 or claim 12, wherein the compound of formula (II) is produced by: (i) reacting a compound of formula (III)

with two or more coupling agents to produce an activated compound; Y (ii) reacting the activated compound with an amine having the formula R2R3NH or R2R3ND, wherein R1, R2 and R3 are as defined in claim 11. The method of claim 13, wherein the two or more coupling agents comprise an additive coupling agent, preferably wherein the two or more coupling agents comprise a carbodiimide. The method of claim 14, wherein: (i) the carbodiimide is selected from the group consisting of N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide, N -(3-dimethylaminopropyl)- N -ethylcarbodiimide.HCl, dicyclohexylcarbodiimide and diisopropylcarbodiimide, preferably wherein the carbodiimide is N —(3-dimethylaminopropyl)— N —ethylcarbodiimide.HCl; and/or (ii) the additive coupling agent is selected from the group consisting of 1-hydroxybenzotriazole, hydroxy-3,4-dihydro-4-oxo-1,2,3-benzotriazine, N-hydroxysuccinimide, 1-hydroxy- 7-aza-1H-benzotriazole, ethyl 2-cyano-2-(hydroxymino)acetate and 4-(N,N-dimethylamino)pyridine, preferably wherein the additive coupling agent is 1-hydroxybenzotriazole.