WO2017099969A1

WO2017099969A1 - Tetrahydroquinoxaline m1 receptor positive allosteric modulators

Info

Publication number: WO2017099969A1
Application number: PCT/US2016/062658
Authority: WO
Inventors: Douglas C. Beshore; Wen-Lian Wu
Original assignee: Merck Sharp and Dohme Ltd; Merck Sharp and Dohme LLC
Current assignee: Organon Pharma UK Ltd; Merck Sharp and Dohme LLC
Priority date: 2015-12-10
Filing date: 2016-11-18
Publication date: 2017-06-15
Anticipated expiration: 2018-06-10

Abstract

The present invention is directed to tetrahydroquinoxaline compounds of formula (I) which are M1 receptor positive allosteric modulators and that are useful in the treatment of diseases in which the M1 receptor is involved, such as Alzheimer's disease, schizophrenia, pain or sleep disorders. The invention is also directed to pharmaceutical compositions comprising the compounds and to the use of the compounds and compositions in the treatment of diseases mediated by the M1 receptor.

Description

TITLE OF THE INVENTION

TETRAHYDROQUINOXALINE Ml RECEPTOR POSITIVE ALLOSTERIC MODULATORS

BACKGROUND OF THE INVENTION

The invention is directed to a class of tetrahydroquinoxaline compounds, their salts, pharmaceutical compositions comprising them and their use in therapy of the human body. In particular, the invention is directed to a class of tetrahydroquinoxaline compounds which are muscarinic Ml receptor positive allosteric modulators, and hence are useful in the treatment of Alzheimer's Disease and other diseases mediated by the muscarinic Ml receptor.

SUMMARY OF THE INVENTION

Alzheimer's Disease is a common neurodegenerative disease affecting the elderly, resulting in progressive memory impairment, loss of language and visuospatial skills, and behavior deficits. Characteristics of the disease include degeneration of cholinergic neurons in the cerebral cortex, hippocampus, basal forebrain, and other regions of the brain, neurofibrillary tangles, and accumulation of the amyloid β peptide (Αβ). Αβ is a 39-43 amino acid produced in the brain by processing of the beta-amyloid precursor protein (APP) by the beta-amyloid protein cleaving enzyme ("beta secretase" or "BACE") and gamma-secretase. The processing leads to accumulation of Αβ in the brain.

Cholinergic neurotransmission involves the binding of acetylcholine either to the nicotinic acetylcholine receptor (nAChR) or to the muscarinic acetylcholine receptor (mAChR). It has been hypothesized that cholinergic hypofunction contributes to the cognitive deficits of patients suffering from Alzheimer's Disease. Consequently, acetyl cholinesterase inhibitors, which inhibit acetylcholine hydrolysis, have been approved in the United States for use in the treatment of the cognitive impairments of Alzheimer's Disease patients. While acetyl cholinesterase inhibitors have provided some cognitive enhancement in Alzheimer's Disease patients, the therapy has not been shown to change the underlying disease pathology.

A second potential pharmacotherapeutic target to counteract cholinergic hypofunction is the activation of muscarinic receptors. Muscarinic receptors are prevalent throughout the body. Five distinct muscarinic receptors (M1-M5) have been identified in mammals. In the central nervous system, muscarinic receptors are involved in cognitive, behavior, sensory, motor and autonomic functions. The muscarinic Ml receptor, which is prevalent in the cerebral cortex, hippocampus and striatum, has been found to have a major role in cognitive processing and is believed to have a role in the pathophysiology of Alzheimer's Disease. See Eglen et al, TRENDS in Pharmacological Sciences, 2001, 22:8, 409-414. In addition, unlike acetyl cholinesterase inhibitors, which are known to provide only symptomatic treatment, Ml agonists also have the potential to treat the underlying disease mechanism of Alzheimer's Disease. The cholinergic hypothesis of Alzheimer's Disease is linked to both β-amyloid and hyperphosphorylated tau protein. Formation of β-amyloid may impair the coupling of the muscarinic receptor with G-proteins. Stimulation of the Ml muscarinic receptor has been shown to increase formation of the neuroprotective aAPPs fragment, thereby preventing the formation of the Αβ peptide. Thus, Ml agonists may alter APP processing and enhance aAPPs secretion. See Fisher, Jpn J Pharmacol, 2000, 84: 101-112.

However, Ml ligands which have been developed and studied for Alzheimer's Disease have produced side effects common to other muscarinic receptor ligands, such as sweating, nausea and diarrhea. See Spalding et al, Mol Pharmacol, 2002, 61 :6, 1297-1302. See also WO2005056552, WO2005030188 and WO2007067489.

The muscarinic receptors are known to contain one or more allosteric sites, which may alter the affinity with which muscarinic ligands bind to the primary binding or

orthosteric sites. See, e.g., S. Lazareno et al, Mol Pharmacol, 2002, 62:6, 1491-1505; S.

Lazareno et al, Mol Pharmacol, 2000, 58, 194-207.

Thus the compounds of the invention, which are muscarinic Ml receptor positive allosteric modulators, are believed to be useful in the treatment of Alzheimer's Disease and other diseases mediated by the muscarinic Ml receptor.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to novel tetrahydroquinoxaline compounds of generic formula (I) described below, or pharmaceutically acceptable salts thereof, which are useful as an Ml receptor positive allosteric modulator.

The invention is further directed to methods of treating a patient (preferably a human) for diseases or disorders in which the Ml receptor is involved, such as Alzheimer's disease, cognitive impairment, schizophrenia, pain disorders and sleep disorders, by administering to the patient a therapeutically effective amount of a compound of general formula (I), or a

pharmaceutically acceptable salt thereof. The invention is also directed to pharmaceutical compositions which include an effective amount of a compound of formula (I), or a

pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable carrier, and the use of the compounds and pharmaceutical compositions of the invention in the treatment of such diseases.

In one embodiment, the invention is directed to N-methyl tetrahydroquinoline compounds of general formula (I)

or pharmaceutically acceptable salts thereof, wherein w is 2, 3, 4, 5, or 6;

V is CH₂, or

one or two of V is S, N, or O, and the others are CH₂;

X, Y, Q, and Z are each CR³, or one or two of X, Y, Q and Z is N and the others are CR ;

p is 0, 1, 2, or 3; R³ is hydrogen, halogen, -C1.4 alkyl, -S(Ci -6 alkyl), or hydroxy; R¹ is selected from

hydrogen,

aryl,

heteroaryl,

halogen,

-CN,

-O-Ci-6 alkyl,

-Ci-6 alkyl,

-C2-6 alkenyl,

-S(Ci-6 alkyl), -S(=0)n-R⁴, and

-NR⁵R⁶,

wherein said aryl, heteroaryl, alkyl, and alkenyl moiety is substituted with 0, 1, 2, or 3 groups selected from

halogen,

hydroxy,

-O-C l-6 alkyl,

-Ci-6 alkyl,

-C(=0)-(0)m-R⁷,

- R⁵R⁶,

-S(C 1-6 alkyl),

-S(=0)_n-R⁴, and

oxo;

each m is 0 or 1;

each n is 0, 1, or 2;

each R² is independently selected from

halogen,

hydroxy,

-O-Ci-6 alkyl,

-C 1-6 alkyl,

-S(Ci-6 alkyl),

-S(=0)_n-R⁴,

-C2-6 alkenyl,

-CN,

-C(=0)-(0)_m-R⁷, - R⁵R⁶,

oxo,

aryl,

heteroaryl, and

heterocycloalkyl,

wherein said aryl, heteroaryl, alkyl, heterocycloalkyl, and alkenyl moiety is substituted with 0, 1, 2, or 3 groups selected from

halogen,

hydroxy,

-S(Ci-6 alkyl),

-O-Ci-6 alkyl, and

-Ci-6 alkyl;

R⁴ and R⁷ are each independently selected from

hydrogen, -Ci-6 alkyl, and -(CH₂)_n-aryl,

wherein said R⁴ and R⁷, the alkyl or aryl moiety is substituted with 0, 1, 2 or 3

halogen,

cyano,

-O-Ci -6 alkyl, or -O-Ci -6 haloalkyl; and R⁵ and R⁶ are each independently selected from

hydrogen, -Ci-6 alkyl, -C3.6 cycloalkyl, -C(=0)-(0)_m-R⁸, -S(=0)_n-R",

wherein R⁸ are each independently selected from

hydrogen,

-Ci-6 alkyl, and -(CH₂)_n-aryl,

or R⁵ and R⁶ are linked together with the nitrogen to which they are both attached to form a 3-6 membered ring.

Representative compounds of the instant invention include, but are not limited to, the following compounds or their pharmaceutically acceptable salts thereof:

3-(2-hydroxycyclohexyl)-6-((6-methylpyridin-3-yl)methyl)-2,3,5,6-tetrahydro-lH-pyrazino[l,2- a]quinoxaline-l,4(4aH)-dione;

3-((l,S',2₎S)-2-hydroxycyclohexyl)-6-((6-methylpyridin-3-yl)methyl)-2,3,5,6-tetrahydro-lH- pyrazino[ 1 ,2-a]quinoxaline- 1 ,4(4aH)-dione; and

3-((lR,2R)-2-hydroxycyclohexyl)-6-((6-methylpyridin-3-yl)methyl)-2,3,5,6-tetrahydro-lH- pyrazino[ 1 ,2-a]quinoxaline- 1 ,4(4aH)-dione.

In one embodiment of the invention, w is 3, 4, 5, or 6. In variant of this embodiment, w is 4 or 5. In yet another embodiment of the invention, w is 2.

In one aspect of the invention comprising the compounds of formula (I), p is 0, 1, or 2. In another embodiment, p is 0 or 1. In a variant of this embodiment, p is 0. In another embodiment of the invention, n is 1 or 2. In another embodiment of the compounds of formula (I), n is 0.

One embodiment of the invention includes m is 0. Another embodiment of the compounds of formula (I) comprises m is 1.

In yet another embodiment of the compounds of formula (I), V is CH₂. In another embodiment, one or two of V is N and the other are CH₂. In yet another embodiment of the invention, one or two of V is S, and the others are CH₂.

In still another embodiment of the invention, one or two of V is O, and the others are CH₂. In yet another embodiment of the invention, one V is S, another is O, and the others are CH₂. In still another embodiment of the invention, in the compounds of formula (I), one V is N, another is O, and the others are CH₂.

In one embodiment, R⁵ and R⁶ are each independently selected from hydrogen, -C i-6 alkyl, and -C3.6 cycloalkyl. In a variant of this embodiment, R⁵ and R⁶ are each independently selected from hydrogen, -Ci-6 alkyl, and -C3-6 cycloalkyl.

In one embodiment, R⁴ and R⁷ are each independently selected from hydrogen and -C \. 6 alkyl, and wherein said alkyl moiety is substituted with 0, 1, 2 or 3 halogen, cyano, -O-C i -6 alkyl, or -O-C i-6 haloalkyl.

In another embodiment, R⁴ and R⁷ are each independently selected from hydrogen, methyl, ethyl, and propyl, and wherein said alkyl moiety is substituted with 0, 1, 2 or 3 halogen, cyano, -O-C i-6 alkyl, or -O-C i-6 haloalkyl.

In one embodiment each R⁸ is independently selected from hydrogen and -Ci -6 alkyl, and wherein said alkyl moiety is substituted with 0, 1, 2 or 3 halogen, cyano, -O-C i-6 alkyl, or - O-C i-6 haloalkyl.

In another embodiment each R⁸ is independently selected from hydrogen, methyl, ethyl, and propyl, and wherein said alkyl moiety is substituted with 0, 1, 2 or 3 halogen, cyano, -O-C i- 6 alkyl, or -O-C i-6 haloalkyl.

In one embodiment of the compounds of formula (I), each R² is independently selected from halogen, hydroxy, -O-Ci -6 alkyl, -C i -6 alkyl, -C2-6 alkenyl, -CN, - R⁵R⁶, aryl, -S(C i _6 alkyl), heteroaryl, and heterocycloalkyl, wherein said aryl, heteroaryl, alkyl, and

heterocycloalkyl, moiety is substituted with 0, 1, 2, or 3 groups selected from halogen, hydroxy, -S(Ci _6 alkyl), -O-C i -6 alkyl, and -C i -6 alkyl.

In yet another embodiment of the invention, each R² is independently selected from halogen, -0-C i .3 alkyl, -S(C i -6 alkyl), and -C i .3 alkyl, wherein said alkyl moiety is substituted with 0, 1, 2, or 3 groups selected from halogen, hydroxy, -S(C i-6 alkyl), -O-C3-6 alkyl, and - Ci -6 alkyl.

In yet another embodiment, each R² is independently selected from fluorine, chlorine, thiom ethyl, thioethyl, thiopropyl, methoxy, ethoxy, methyl, ethyl, and propyl.

In one embodiment of the invention, in the compounds of formula (I), R¹ is selected from hydrogen, aryl, heteroaryl, halogen, -CN, -O-C i-6 alkyl, -C i-6 alkyl, -C2-6 alkenyl, -S(Ci-6 alkyl), -S(=0)_n-R⁴, and -NR⁵R⁶, wherein said aryl, heteroaryl, alkyl, and alkenyl moiety is substituted with 0, 1, 2, or 3 groups selected from halogen, hydroxy, -O-Ci-6 alkyl, -Ci-6 alkyl, -C(=0)-(0)_m-R⁷, - R⁵R⁶,-S(Ci-6 alkyl), and oxo.

In another embodiment of the invention, R¹ is selected from aryl, heteroaryl, halogen, -O-C i -6 alkyl, -C i -6 alkyl, and -S(C i -6 alkyl), wherein said aryl, heteroaryl, and alkyl moiety is substituted with 0, 1, 2, or 3 groups selected from halogen, hydroxy, -O-Ci-6 alkyl, -Ci-6 alkyl, - -S(Ci -6 alkyl), and oxo.

In yet another embodiment of the invention, R¹ is selected from aryl and hetoroaryl, wherein said aryl and heteroaryl is substituted with 0, 1, 2 or 3 groups selected from halogen, hydroxy, -O-C i -6 alkyl, -Ci -6 alkyl,- -S(C i -6 alkyl), and oxo.

In yet another embodiment, in the compounds of formula (I), R¹ is selected from 5- to

6- membered aryl, and 5- to 6-membered heteroaryl,wherein said 5- to 6- membered aryl, and 5- to 6-membered heteroaryl are substituted with 0, 1, 2, or 3 groups selected from fluoro, chloro, hydroxy, methoxy, ethoxy, methyl, ethyl, propyl, thiom ethyl, thioethyl, and thiopropyl.

In still another embodiment of the invention, R¹ is selected from 5- to 6- membered aryl, and 5- to 6-membered heteroaryl having 1 or 2 nitrogen atoms, wherein said 5- to 6- membered aryl and 5- to 6-membered heteroaryl is substituted with 0, 1, 2, or 3 groups selected from fluoro, chloro, hydroxy, methoxy, ethoxy, methyl, ethyl, propyl, thiomethyl, thioethyl, and thiopropyl.

In yet another embodiment of the invention, R¹ is selected from phenyl, pyrrolyl, pyrazolyl, imidazolyl, 2H-imidazolyl, pyridinyl, pyridazinyl, pyrimidinyl, and pyrazinyl, wherein R¹ is substituted with 0, 1, 2, or 3 groups selected from fluoro, chloro, hydroxy, methoxy, ethoxy, methyl, ethyl, propyl, thiomethyl, thioethyl, and thiopropyl.

In another embodiment, R¹ is -Ci-6 alkyl substituted with 0, 1, 2, or 3 groups selected from fluoro, chloro, hydroxy, methoxy, ethoxy, thiomethyl, thioethyl, and thiopropyl. In a variant of this embodiment, R¹ is methyl, ethyl, propyl or butyl, substituted with 0, 1, 2, or 3 groups selected from fluoro, chloro, hydroxy, methoxy, ethoxy, thiomethyl, thioethyl, and thiopropyl. In yet another embodiment, R¹ is methyl.

In one embodiment, the invention is directed to N-methyl tetrahydroquinoline

compounds of general formula (II)

or pharmaceutically acceptable salts thereof, wherein

X^b, Y^b, Q^b, and Z^b are each CR^¾, or one or two of X^b, Y^b, Q^b, and Z^b is N and the others are CR^¾; p is 0, 1, 2, or 3;

a

R is hydrogen, fluorine, chlorine, -Ci-4 alkyl, -S(Ci-6 alkyl), or hydroxy;

R^lb is selected from hydrogen, aryl, heteroaryl, and -Ci-6 alkyl, wherein said aryl, heteroaryl, and alkyl, moiety is substituted with 0, 1, 2, or 3 groups selected from halogen, hydroxy,

-O-Ci-6 alkyl, -Ci-6 alkyl, and -S(Ci-6 alkyl); and each R^2b is independently selected from halogen, hydroxy, -0-Ci .3 alkyl, -C1 -3 alkyl, and

-S(Ci-3 alkyl), wherein said alkyl moiety is substituted with 0, 1, 2, or 3 groups selected from halogen, hydroxy, -S(Ci-3 alkyl), and-O-Ci-3 alkyl.

In another embodiment of the compounds of formula (II):

X^b, Y^b, Q^b, and Z^b are each CH; and R^lb is selected from phenyl, heteroaryl, and -Ci-3 alkyl, wherein said phenyl, heteroaryl, and alkyl, moiety is substituted with 0, 1, 2, or 3 groups selected from halogen, hydroxy, -O-Ci -6 alkyl, -Ci -6 alkyl, and -S(Ci _6 alkyl).

In yet another embodiment of the invention, R^lb is selected from phenyl, pyrrolyl, pyrazolyl, imidazolyl, 2H-imidazolyl, pyridinyl, pyridazinyl, pyrimidinyl, and pyrazinyl, wherein R^lb is substituted with 0, 1, 2, or 3 groups selected from fluoro, chloro, hydroxy, methoxy, ethoxy, methyl, ethyl, propyl, thiom ethyl, thioethyl, and thiopropyl. In another embodiment, R is -Ci-6 alkyl substituted with 0, 1, 2, or 3 groups selected from fluoro, chloro, hydroxy, methoxy, ethoxy, thiom ethyl, thioethyl, and thiopropyl. In a variant of this embodiment, R^lb is methyl, ethyl, propyl or butyl, substituted with 0, 1, 2, or 3 groups selected from fluoro, chloro, hydroxy, methoxy, ethoxy, thiomethyl, thioethyl, and thiopropyl. In yet another embodiment, R^lb is methyl.

The invention is also directed to methods of treating a patient (preferably a human) for diseases or disorders in which the Ml receptor is involved, such as Alzheimer's Disease, cognitive impairment, schizophrenia, pain disorders and sleep disorders, by administering to the patient a therapeutically effective amount of a compound of formula (I), or a pharmaceutically acceptable salt thereof.

The invention is also directed to the use of a compound of formula (I), for treating a disease or disorder in which the Ml receptor is involved, such as Alzheimer's Disease, cognitive impairment, schizophrenia, pain disorders and sleep disorders, by administering to the patient a compound of formula (I), or a pharmaceutically acceptable salt thereof.

The invention is also directed to medicaments or pharmaceutical compositions for the treatment of diseases or disorders in a patient (preferably a human) in which the Ml receptor is involved, such as Alzheimer's Disease, cognitive impairment, schizophrenia, pain disorders, and sleep disorders, which comprise a compound of formula (I), or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable carrier.

The invention is also directed to a method for the manufacture of a medicament or a pharmaceutical composition for treating diseases in which Ml receptor is involved, such as Alzheimer's Disease, cognitive impairment, schizophrenia, pain disorders, and sleep disorders, comprising combining a compound of formula (I), or a pharmaceutically acceptable salt thereof, with a pharmaceutically acceptable carrier.

When any variable (e.g. aryl, heteroaryl, R1, R^, etc.) occurs more than one time in any constituent, its definition on each occurrence is independent at every other occurrence. Also, combinations of substituents/or variables are permissible only if such combinations result in stable compounds.

The wavy line 'w x. , as used herein, indicates a point of attachment to the rest of the compound. Lines drawn into the ring systems, such as, for example:

indicate that the indicated line (bond) may be attached to any of the substitutable ring carbon atoms.

The term "alkyl," as used herein, refers to an aliphatic hydrocarbon group having one of its hydrogen atoms replaced with a bond. An alkyl group may be straight or branched and contain from about 1 to about 10 carbon atoms. In different embodiments, an alkyl group contains from 1 to 6 carbon atoms (Ci-₆ alkyl) or from about 1 to about 3 carbon atoms (C₁-3 alkyl). Non-limiting examples of alkyl groups include methyl, ethyl, n-propyl, isopropyl, n- butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, neopentyl, isopentyl, n-hexyl, isohexyl and neohexyl. In one embodiment, an alkyl group is linear. In another embodiment, an alkyl group is branched. Unless otherwise indicated, an alkyl group is unsubstituted.

The term "alkenyl," as used herein, refers to an aliphatic hydrocarbon group containing at least one carbon-carbon double bond and having one of its hydrogen atoms replaced with a bond. An alkenyl group may be straight or branched and contain from about 2 to about 15 carbon atoms. In one embodiment, an alkenyl group contains from about 2 to about 12 carbon atoms. In another embodiment, an alkenyl group contains from about 2 to about 6 carbon atoms. Non- limiting examples of alkenyl groups include ethenyl, propenyl, n-butenyl, 3-methylbut-2-enyl, n- pentenyl, octenyl and decenyl. Unless otherwise indicated, an alkenyl group is unsubstituted.

Except where noted, the term "aryl" is intended to mean any stable monocyclic or bicyclic carbon ring of up to 12 atoms in each ring, wherein at least one ring is aromatic.

Examples of such aryl elements include phenyl, naphthyl, tetrahydronaphthyl and indanyl. In one embodiment, an aryl group contains from about 6 to about 10 carbon atoms. In one embodiment, an aryl group can be optionally fused to a cycloalkyl or cycloalkanoyl. Non- limiting examples of aryl groups include phenyl and naphthyl. In one embodiment, an aryl group is phenyl. Unless otherwise indicated, an aryl group is unsubstituted.

Except where noted, the term "cycloalkyl" means a monocyclic or bicyclic saturated aliphatic hydrocarbon group having the specified number of carbon atoms. For example, "cycloalkyl" includes cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, and so on. The term "3 to 7-membered cycloalkyl" refers to a cycloalkyl group having from 3 to 7 ring carbon atoms. Unless otherwise indicated, a cycloalkyl group is unsubstituted.

The term "C i-6" includes alkyls containing 6, 5, 4, 3, 2, or 1 carbon atoms.

The term "alkoxy" as used herein, refers to an -O-alkyl group, wherein an alkyl group is as defined above. Non-limiting examples of alkoxy groups include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy and t-butoxy. An alkoxy group is bonded via its oxygen atom. The term "halo," or "halogen" as used herein, means -F, -CI, -Br or -I. In one embodiment, a halo group is -F or -CI. In another embodiment, a halo group is -F.

Except where noted, the term "heteroaryl", as used herein, represents a stable monocyclic or bicyclic ring system of up to 10 atoms in each ring, wherein at least one ring is aromatic, and at least one ring contains from 1 to 4 heteroatoms selected from the group consisting of O, N and S. Bicyclic heteroaryl ring systems include fused ring systems, where two rings share two atoms, and spiro ring systems, where two rings share one atom. Heteroaryl groups within the scope of this definition include but are not limited to: benzoimidazolyl, benzofuranyl, benzofurazanyl, benzopyrazolyl, benzotriazolyl, benzothiophenyl, benzoxazolyl, carbazolyl, carbolinyl, cinnolinyl, furanyl, indolinyl, indolyl, indolazinyl, indazolyl, isobenzofuranyl, isoindolyl, isoquinolyl, isothiazolyl, isoxazolyl, naphthpyridinyl, oxadiazolyl, oxazolyl, oxazoline, isoxazoline, pyranyl, pyrazinyl, pyrazolyl, pyridazinyl, pyridopyridinyl, pyridyl, pyrimidinyl, pyrrolyl, quinazolinyl, quinolyl, quinoxalinyl, tetrazolyl, tetrazolopyridyl, thiadiazolyl, thiazolyl, thienyl, triazolyl, dihydrobenzoimidazolyl, dihydrobenzofuranyl, dihydrobenzothiophenyl, dihydrobenzoxazolyl, dihydroindolyl, dihydroquinolinyl, methylenedioxybenzene,

benzothiazolyl, benzothienyl, quinolinyl, isoquinolinyl, oxazolyl, tetra-hydroquinoline and 3- oxo-3,4dihydro-2N-benzo[b][l,4]thiazine. If the heteroaryl contains nitrogen atoms, it is understood that the corresponding N-oxides thereof are also encompassed by this definition.

The term "heterocycloalkyl", as used herein except where noted, represents a non- aromatic cyclic or polycyclic group having from five to twelve ring atoms selected from C, O, N or S, at least one of which is O, N or S. Examples of heterocycloalkyls include azetidinyl, pyrrolidinyl, piperidinyl, piperazinyl, morpholinyl, pyranyl, tetrahydrofuranyl, imidazolinyl, pyrolidin-2-one, piperidin-2-one, and thiomorpholinyl.

The term "heteroatom" means O, S or N, selected on an independent basis.

A moiety that is substituted is one in which one or more hydrogens have been

independently replaced with another chemical substituent. As a non-limiting example, substituted phenyls include 2-flurophenyl, 3,4-dichlorophenyl, 3-chloro-4-fluoro-phenyl, 2,4- difluoro-3-propylphenyl. As another non-limiting example, substituted n-octyls include 2,4 dimethyl-5-ethyl-octyl and 3-cyclopentyloctyl. Included within this definition are methylenes (- CH₂-) substituted with oxygen to form carbonyl (-CO-).

The term "thioalkyl" means -Salkyl, -S(Ci-6 alkyl), wherein the alkyl group may be straight or branched and contain from about 1 to about 10 carbon atoms.

"Celite®" (Fluka) diatomite is diatomaceous earth, and can be referred to as "celite".

Unless otherwise stated, as employed herein, when a moiety (e.g., cycloalkyl, hydrocarbyl, aryl, alkyl, heteroaryl, heterocyclic, urea, etc.) is described as "optionally substituted" it is meant that the group optionally has from one to four, preferably from one to three, more preferably one or two, non-hydrogen substituents. It should also be noted that any carbon as well as heteroatom with unsatisfied valences in the text, schemes, examples and tables herein is assumed to have the sufficient number of hydrogen atom(s) to satisfy the valences.

The term "mammal" "mammalian" or "mammals" includes humans, as well as animals, such as dogs, cats, horses, pigs and cattle.

All patents, patent applications and publications cited herein, whether supra or infra, are hereby incorporated by reference in their entirety and are deemed representative of the prevailing state of the art.

As used in this specification and the appended claims, the singular forms "a," "an" and "the" include plural references unless the content clearly dictates otherwise. Thus, for example, reference to "a primer" includes two or more such primers, reference to "an amino acid" includes more than one such amino acid, and the like.

The present invention encompasses all stereoisomeric forms of the compounds of Formula I and Formula II. Centers of asymmetry that are present in the compounds of Formula I and Formula II can all independently of one another have (R) configuration or (S) configuration. When bonds to the chiral carbon are depicted as straight lines in the structural Formulas of the invention, it is understood that both the (R) and (S) configurations of the chiral carbon, and hence both enantiomers and mixtures thereof, are embraced within the Formula. Similarly, when a compound name is recited without a chiral designation for a chiral carbon, it is understood that both the (R) and (S) configurations of the chiral carbon, and hence individual enantiomers and mixtures thereof, are embraced by the name. The production of specific stereoisomers or mixtures thereof may be identified in the Examples where such stereoisomers or mixtures were obtained, but this in no way limits the inclusion of all stereoisomers and mixtures thereof from being within the scope of this invention.

A solid line, ^^m ,as a bond generally indicates a mixture of, or either of, the possible isomers, e.g., containing (R)- and (S)- stereochemistry. For example:

Here, the wedged line

, represents that the bond is located in front of the plane and the hatched line, _****

represents that the bond is a behind the plane bond.

The compounds of the present invention may contain one or more asymmetric centers and can thus occur as "stereoisomers" including racemates and racemic mixtures, enantiomeric mixtures, single enantiomers, diastereomeric mixtures and individual diastereomers. Additional asymmetric centers may be present depending upon the nature of the various substituents on the molecule. Each such asymmetric center will independently produce two optical isomers and it is intended that all of the possible optical isomers and diastereomers in mixtures and as pure or partially purified compounds are included within the scope of this invention. The present invention is meant to comprehend all such isomeric forms of these compounds. When bonds to the chiral carbon are depicted as straight lines in the Formulas of the invention, it is understood that both the (R) and (S) configurations of the chiral carbon, and hence both enantiomers and mixtures thereof, are embraced within the Formula. For example, Formula I shows the structure of the class of compounds without specific stereochemistry. When the compounds of the present invention contain one chiral center, the term "stereoisomer" includes both enantiomers and mixtures of enantiomers, such as the specific 50:50 mixture referred to as racemic mixtures.

Diastereomeric mixtures can be separated into their individual diastereomers on the basis of their physical chemical differences by methods well known to those skilled in the art, such as, for example, by chromatography and/or fractional crystallization. Enantiomers can be separated by converting the enantiomeric mixture into a diastereomeric mixture by reaction with an appropriate optically active compound (e.g., chiral auxiliary such as a chiral alcohol or Mosher's acid chloride), separating the diastereomers and converting (e.g., hydrolyzing) the individual diastereomers to the corresponding pure enantiomers. Also, some of the compounds of Formula (I) may be atropisomers (e.g., substituted biaryls) and are considered as part of this invention. Enantiomers can also be separated by use of chiral FIPLC column.

It is also possible that the compounds of Formula (I) may exist in different tautomeric forms, and all such forms are embraced within the scope of the invention. Also, for example, all keto-enol and imine-enamine forms of the compounds are included in the invention.

All stereoisomers (for example, optical isomers and the like) of the present compounds, such as those which may exist due to asymmetric carbons on various substituents, including enantiomeric forms (which may exist even in the absence of asymmetric carbons), rotameric forms, atropisomers, and diastereomeric forms, are contemplated within the scope of this invention, as are positional isomers (such as, for example, 4-pyridyl and 3-pyridyl). (For example, if a compound of Formula (I) incorporates a double bond or a fused ring, both the cis- and trans-forms, as well as mixtures, are embraced within the scope of the invention. Also, for example, all keto-enol and imine-enamine forms of the compounds are included in the invention.) Individual stereoisomers of the compounds of the invention may, for example, be substantially free of other isomers, or may be admixed, for example, as racemates or with all other, or other selected, stereoisomers. The chiral centers of the present invention can have the S or R configuration as defined by the IUPAC 1974 Recommendations.

The use of the terms "salt", "solvate", "ester", "prodrug" and the like, is intended to equally apply to the salt, solvate, ester and prodrug of enantiomers, stereoisomers, rotamers, tautomers, positional isomers, racemates or prodrugs of the inventive compounds. In the present application when a particular stereomeric compound is named using an "and" in the stereomeric designation, for example, (S and R)-, the "and" indicates a racemic mixture of the enantiomers. That is, the individual enantiomers were not individually isolated.

When the stereomeric nomenclature includes "or", for example, (S or R)-, the "or" indicates that chiral resolution of racemate into individual enantiomers was accomplished but the actual optical activity of the specific enantiomer was not determined.

The independent syntheses of these diastereomers or their chromatographic separations may be achieved as known in the art by appropriate modification of the methodology disclosed herein. Their absolute stereochemistry may be determined by the x-ray crystallography of crystalline products or crystalline intermediates which are derivatized, if necessary, with a reagent containing an asymmetric center of known absolute configuration. If desired, racemic mixtures of the compounds may be separated so that the individual enantiomers are isolated. The separation can be carried out by methods well known in the art, such as the coupling of a racemic mixture of compounds to an enantiomerically pure compound to form a diastereomeric mixture, followed by separation of the individual diastereomers by standard methods, such as fractional crystallization or chromatography. The coupling reaction is often the formation of salts using an enantiomerically pure acid or base. The diasteromeric derivatives may then be converted to the pure enantiomers by cleavage of the added chiral residue. The racemic mixture of the compounds can also be separated directly by chromatographic methods utilizing chiral stationary phases, which methods are well known in the art. Alternatively, any enantiomer of a compound can be obtained by stereoselective synthesis using optically pure starting materials or reagents of known configuration by methods well known in the art.

In the compounds of generic Formula I, the atoms may exhibit their natural isotopic abundances, or one or more of the atoms may be artificially enriched in a particular isotope having the same atomic number, but an atomic mass or mass number different from the atomic mass or mass number predominantly found in nature. The present invention is meant to include all suitable isotopic variations of the compounds of generic Formula I. For example, different isotopic forms of hydrogen (H) include protium (lH) and deuterium (2H). Protium is the predominant hydrogen isotope found in nature. Enriching for deuterium may afford certain therapeutic advantages, such as increasing in vivo half-life or reducing dosage requirements, or may provide a compound useful as a standard for characterization of biological samples.

Isotopically-enriched compounds within generic Formula I can be prepared without undue experimentation by conventional techniques well known to those skilled in the art or by processes analogous to those described in the Schemes and Examples herein using appropriate isotopically-enriched reagents and/or intermediates. The compounds of the invention may be prepared according to the following reaction Schemes, in which variables are as defined before or are derived, using readily available starting materials, from reagents and conventional synthetic procedures. It is also possible to use variants which are themselves known to those of ordinary skill in organic synthesis art, but are not mentioned in greater detail.

The present invention also provides a method for the synthesis of compounds useful as intermediates in the preparation of compounds of the invention.

During any of the above synthetic sequences it may be necessary or desirable to protect sensitive or reactive groups on any of the molecules concerned. This may be achieved by means of conventional protecting groups, such as those described in Protective Groups in Organic Chemistry, ed. J.F.W.McOmie, Plenum Press, 1973, and T.W. Greene & P/G.M. Wuts,

Protective Groups in Organic Synthesis, John Wiley & Sons, 1999. The protecting groups may be removed at a convenient sequent stage using methods known from the art.

Specific embodiments of the compounds of the invention, and methods of making them, are described in the Examples herein.

The term "substantially pure" means that the isolated material is at least 90% pure, and preferably 95% pure, and even more preferably 99% pure as assayed by analytical techniques known in the art.

As used herein, the term "muscarinic Ml receptor " refers to one of the five subtypes of the muscarinic acetylcholine receptor, which is from the superfamily of G-protein coupled receptors. The family of muscarinic receptors is described, for example, in Pharmacol Ther, 1993, 58:319-379; Eur J Pharmacol, 1996, 295:93-102, and Mol Pharmacol, 2002, 61 : 1297- 1302. The muscarinic receptors are known to contain one or more allosteric sites, which may alter the affinity with which muscarinic ligands bind to the primary binding or

orthosteric sites. See, e.g., S. Lazareno et al, Mol Pharmacol, 2002, 62:6, 1491-1505.

As used herein, the terms "positive allosteric modulator" and "allosteric potentiator" are used interchangeably, and refer to a ligand which interacts with an allosteric site of a receptor to activate the primary binding site. The compounds of the invention are positive allosteric modulators of the muscarinic Ml receptor. For example, a modulator or

potentiator may directly or indirectly augment the response produced by the endogenous ligand (such as acetylcholine or xanomeline) at the orthosteric site of the muscarinic Ml receptor in an animal, in particular, a human.

The actions of ligands at allosteric receptor sites may also be understood according to the "allosteric ternary complex model," as known by those skilled in the art. The allosteric ternary complex model is described with respect to the family of muscarinic receptors in Birdsall et al, Life Sciences, 2001, 68:2517-2524. For a general description of the role of allosteric binding sites, see Christopoulos, Nature Reviews: Drug Discovery, 2002, 1 : 198- 210. It is believed that the compounds of the invention bind to an allosteric binding site that is distinct from the orthosteric acetylcholine site of the muscarinic Ml receptor, thereby augmenting the response produced by the endogenous ligand acetylcholine at the orthosteric site of the Ml receptor. It is also believed that the compounds of the invention bind to an allosteric site which is distinct from the xanomeline site of the muscarinic Ml receptor, thereby augmenting the response produced by the endogenous ligand xanomeline at the orthosteric site of the Ml receptor.

The term "pharmaceutically acceptable salts" refers to salts prepared from

pharmaceutically acceptable non-toxic bases or acids including inorganic or organic bases and inorganic or organic acids. The compounds of the invention may be mono, di or tris salts, depending on the number of acid functionalities present in the free base form of the compound. Free bases and salts derived from inorganic bases include aluminum, ammonium, calcium, copper, ferric, ferrous, lithium, magnesium, manganic salts, manganous, potassium, sodium, zinc, and the like.

Salts in the solid form may exist in more than one crystal structure, and may also be in the form of hydrates. Salts derived from pharmaceutically acceptable organic non-toxic bases include salts of primary, secondary, and tertiary amines, substituted amines including naturally occurring substituted amines, cyclic amines, and basic ion exchange resins, such as arginine, betaine, caffeine, choline, N,N'-dibenzylethylene-diamine, diethylamine, 2-diethylaminoethanol, 2-dimethylaminoethanol, ethanolamine, ethylenediamine, N-ethylmorpholine, N-ethylpiperidine, glucamine, glucosamine, histidine, hydrabamine, isopropylamine, lysine, methylglucamine, morpholine, piperazine, piperidine, polyamine resins, procaine, purines, theobromine, triethylamine, trimethylamine, tripropylamine, tromethamine, and the like.

When the compound of the present invention is basic, salts may be prepared from pharmaceutically acceptable non-toxic acids, including inorganic and organic acids. Such acids include acetic, trifluoroacetic, benzenesulfonic, benzoic, camphorsulfonic, citric, ethanesulfonic, fumaric, gluconic, glutamic, hydrobromic, hydrochloric, isethionic, lactic, maleic, malic, mandelic, methanesulfonic, mucic, nitric, pamoic, pantothenic, phosphoric, succinic, sulfuric, tartaric, /?ara-toluenesulfonic acid, and the like.

Suitable pharmaceutically acceptable salts include ammonium, sodium, potassium, hydrochloride, hydrobromide and fumarate.

The present invention is directed to the use of the compounds of formula (I) disclosed herein as Ml allosteric modulators in a patient or subject such as a mammal in need of such activity, comprising the administration of an effective amount of the compound. In addition to humans, a variety of other mammals can be treated according to the method of the present invention. The compounds of the present invention have utility in treating or ameliorating

Alzheimer's disease. The compounds may also be useful in treating or ameliorating other diseases mediated by the muscarinic Ml receptor, such as schizophrenia, sleep disorders, pain disorders (including acute pain, inflammatory pain and neuropathic pain) and cognitive disorders (including mild cognitive impairment). Other conditions that may be treated by the compounds of the invention include Parkinson's Disease, pulmonary hypertension, chronic obstructive pulmonary disease (COPD), asthma, urinary incontinence, glaucoma, schizophrenia, Trisomy 21 (Down Syndrome), cerebral amyloid angiopathy, degenerative dementia, Hereditary Cerebral Hemorrhage with Amyloidosis of the Dutch-Type (HCHWA-D), Creutzfeld- Jakob disease, prion disorders, amyotrophic lateral sclerosis, progressive supranuclear palsy, head trauma, stroke, pancreatitis, inclusion body myositis, other peripheral amyloidoses, diabetes, autism and atherosclerosis.

In preferred embodiments, the compounds of the invention are useful in treating

Alzheimer's Disease, cognitive disorders, schizophrenia, pain disorders and sleep disorders. For example, the compounds may be useful for the prevention of dementia of the Alzheimer's type, as well as for the treatment of early stage, intermediate stage or late stage dementia of the Alzheimer's type.

Potential schizophrenia conditions or disorders for which the compounds of the invention may be useful include one or more of the following conditions or diseases:

schizophrenia or psychosis including schizophrenia (paranoid, disorganized, catatonic or undifferentiated), schizophreniform disorder, schizoaffective disorder, delusional disorder, brief psychotic disorder, shared psychotic disorder, psychotic disorder due to a general medical condition and substance-induced or drug-induced (phencyclidine, ketanine and other dissociative anaesthetics, amphetamine and other psychostimulants and cocaine) psychosispsychotic disorder, psychosis associated with affective disorders, brief reactive psychosis, schizoaffective psychosis, "schizophrenia-spectrum" disorders such as schizoid or schizotypal personality disorders, or illness associated with psychosis (such as major depression, manic depressive (bipolar) disorder, Alzheimer's disease and post-traumatic stress syndrome), including both the positive and the negative symptoms of schizophrenia and other psychoses; cognitive disorders including dementia (associated with Alzheimer's disease, ischemia, multi-infarct dementia, trauma, vascular problems or stroke, HIV disease, Parkinson's disease, Huntington's disease, Pick's disease, Creutzfeldt- Jacob disease, perinatal hypoxia, other general medical conditions or substance abuse); delirium, amnestic disorders or age related cognitive decline. Thus, in another specific embodiment, the present invention provides a method for treating schizophrenia or psychosis comprising administering to a patient in need thereof an effective amount of a compound of the present invention.. At present, the text revision of the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR) (2000, American Psychiatric Association, Washington DC) provides a diagnostic tool that includes paranoid, disorganized, catatonic or undifferentiated schizophrenia and substance-induced psychotic disorder. As used herein, the term "schizophrenia or psychosis" includes treatment of those mental disorders as described in DSM-IV-TR. The skilled artisan will recognize that there are alternative nomenclatures, nosologies and classification systems for mental disorders, and that these systems evolve with medical and scientific progress. Thus the term "schizophrenia or psychosis" is intended to include like disorders that are described in other diagnostic sources.

Potential sleep conditions or disorders for which the compounds of the invention may be useful include enhancing sleep quality; improving sleep quality; augmenting sleep maintenance; increasing the value which is calculated from the time that a subject sleeps divided by the time that a subject is attempting to sleep; decreasing sleep latency or onset (the time it takes to fall asleep); decreasing difficulties in falling asleep; increasing sleep continuity; decreasing the number of awakenings during sleep; decreasing nocturnal arousals; decreasing the time spent awake following the initial onset of sleep; increasing the total amount of sleep; reducing the fragmentation of sleep; altering the timing, frequency or duration of REM sleep bouts; altering the timing, frequency or duration of slow wave (i.e. stages 3 or 4) sleep bouts; increasing the amount and percentage of stage 2 sleep; promoting slow wave sleep; enhancing EEG-delta activity during sleep; increasing daytime alertness; reducing daytime drowsiness; treating or reducing excessive daytime sleepiness; insomnia; hypersomnia; narcolepsy; interrupted sleep; sleep apnea; wakefulness; nocturnal myoclonus; REM sleep interruptions; jet-lag; shift workers' sleep disturbances; dyssomnias; night terror; insomnias associated with depression,

emotional/mood disorders, as well as sleep walking and enuresis, and sleep disorders which accompany aging; Alzheimer's sundowning; conditions associated with circadian rhythmicity as well as mental and physical disorders associated with travel across time zones and with rotating shift-work schedules; conditions due to drugs which cause reductions in REM sleep as a side effect; syndromes which are manifested by non-restorative sleep and muscle pain or sleep apnea which is associated with respiratory disturbances during sleep; and conditions which result from a diminished quality of sleep.

Pain disorders for which the compounds of the invention may be useful include neuropathic pain (such as postherpetic neuralgia, nerve injury, the "dynias", e.g., vulvodynia, phantom limb pain, root avulsions, painful diabetic neuropathy, painful traumatic

mononeuropathy, painful polyneuropathy); central pain syndromes (potentially caused by virtually any lesion at any level of the nervous system); postsurgical pain syndromes (eg, postmastectomy syndrome, postthoracotomy syndrome, stump pain); bone and joint pain (osteoarthritis), repetitive motion pain, dental pain, cancer pain, myofascial pain (muscular injury, fibromyalgia); perioperative pain (general surgery, gynecological), chronic pain, dysmennorhea, as well as pain associated with angina, and inflammatory pain of varied origins (e.g. osteoarthritis, rheumatoid arthritis, rheumatic disease, teno- synovitis and gout), headache, migraine and cluster headache, headache, primary hyperalgesia, secondary hyperalgesia, primary allodynia, secondary allodynia, or other pain caused by central sensitization.

Compounds of the invention may also be used to treat or prevent dyskinesias.

Furthermore, compounds of the invention may be used to decrease tolerance and/or dependence to opioid treatment of pain, and for treatment of withdrawal syndrome of e.g., alcohol, opioids, and cocaine.

The compounds of the present invention may be used in combination with one or more other drugs in the treatment of diseases or conditions for which the compounds of the present invention have utility, where the combination of the drugs together are safer or more effective than either drug alone. Additionally, the compounds of the present invention may be used in combination with one or more other drugs that treat, prevent, control, ameliorate, or reduce the risk of side effects or toxicity of the compounds of the present invention. Such other drugs may be administered, by a route and in an amount commonly used therefor, contemporaneously or sequentially with the compounds of the present invention. Accordingly, the pharmaceutical compositions of the present invention include those that contain one or more other active ingredients, in addition to the compounds of the present invention. The combinations may be administered as part of a unit dosage form combination product, or as a kit or treatment protocol wherein one or more additional drugs are administered in separate dosage forms as part of a treatment regimen.

Examples of combinations of the compounds of the present invention include

combinations with anti-Alzheimer's Disease agents, for example beta-secretase inhibitors; alpha 7 nicotinic agonists, such as ABT089, SSR180711 and MEM63908; ADAM 10 ligands or activators; gamma-secretase inhibitors, such as LY450139 and TAK 070; gamma secretase modulators; tau phosphorylation inhibitors; glycine transport inhibitors; LXR β agonists; ApoE4 conformational modulators; R2B antagonists; androgen receptor modulators; blockers of Αβ oligomer formation; 5-HT4 agonists, such as PRX-03140; 5-HT6 antagonists, such as GSK 742467, SGS-518, FK-962, SL-65.0155, SRA-333 and xaliproden; 5-HTla antagonists, such as lecozotan; p25/CDK5 inhibitors; K1/NK3 receptor antagonists; COX-2 inhibitors; HMG-CoA reductase inhibitors; NSAIDs including ibuprofen; vitamin E; anti-amyloid antibodies (including anti-amyloid humanized monoclonal antibodies), such as bapineuzumab, ACCOOl, CAD 106, AZD3102, H12A11 VI; anti-inflammatory compounds such as (R)-flurbiprofen,

nitroflurbiprofen, D-1251, VP-025, HT-0712 and EHT-202; PPAR gamma agonists, such as pioglitazone and rosiglitazone; CB-1 receptor antagonists or CB-1 receptor inverse agonists, such as AVE1625; antibiotics such as doxycycline and rifampin; N-methyl-D-aspartate (NMDA) receptor antagonists, such as memantine, neramexane and EVT101; cholinesterase inhibitors such as galantamine, rivastigmine, donepezil, tacrine, phenserine, ladostigil and ABT-089; growth hormone secretagogues such as ibutamoren, ibutamoren mesylate, and capromorelin; histamine H3 receptor antagonists such as ABT-834, ABT 829, GSK 189254 and CEP16795;

AMPA agonists or AMPA modulators, such as CX-717, LY 451395, LY404187 and S-18986; PDE IV inhibitors, including MEM1414, HT0712 and AVE8112; GABAA inverse agonists; GSK3p inhibitors, including AZD1080, SAR502250 and CEP16805; neuronal nicotinic agonists; selective Ml agonists; HDAC inhibitors; and microtubule affinity regulating kinase (MARK) ligands; or other drugs that affect receptors or enzymes that either increase the efficacy, safety, convenience, or reduce unwanted side effects or toxicity of the compounds of the present invention.

Examples of combinations of the compounds include combinations with agents for the treatment of schizophrenia, for example in combination with sedatives, hypnotics, anxiolytics, antipsychotics, antianxiety agents, cyclopyrrolones, imidazopyridines, pyrazolopyrimidines, minor tranquilizers, melatonin agonists and antagonists, melatonergic agents, benzodiazepines, barbiturates, 5HT-2 antagonists, and the like, such as: adinazolam, allobarbital, alonimid, alprazolam, amisulpride, amitriptyline, amobarbital, amoxapine, aripiprazole, bentazepam, benzoctamine, brotizolam, bupropion, busprione, butabarbital, butalbital, capuride, carbocloral, chloral betaine, chloral hydrate, clomipramine, clonazepam, cloperidone, clorazepate, chlordiazepoxide, clorethate, chlorpromazine, clozapine, cyprazepam, desipramine, dexclamol, diazepam, dichloralphenazone, divalproex, diphenhydramine, doxepin, estazolam, ethchlorvynol, etomidate, fenobam, flunitrazepam, flupentixol, fluphenazine, flurazepam, fluvoxamine, fluoxetine, fosazepam, glutethimide, halazepam, haloperidol, hydroxyzine, imipramine, lithium, lorazepam, lormetazepam, maprotiline, mecloqualone, melatonin, mephobarbital, meprobamate, methaqualone, midaflur, midazolam, nefazodone, nisobamate, nitrazepam, nortriptyline, olanzapine, oxazepam, paraldehyde, paroxetine, pentobarbital, perlapine, perphenazine, phenelzine, phenobarbital, prazepam, promethazine, propofol, protriptyline, quazepam, quetiapine, reclazepam, risperidone, roletamide, secobarbital, sertraline, suproelone, temazepam, thioridazine, thiothixene, tracazolate, tranylcypromaine, trazodone, triazolam, trepipam, tricetamide, triclofos, trifluoperazine, trimetozine, trimipramine, uldazepam, venlafaxine, zaleplon, ziprasidone, zolazepam, Zolpidem, and salts thereof, and combinations thereof, and the like, or the subject compound may be administered in conjunction with the use of physical methods such as with light therapy or electrical stimulation.

In another embodiment, the subject compound may be employed in combination with levodopa (with or without a selective extracerebral decarboxylase inhibitor such as carbidopa or benserazide), anticholinergics such as biperiden (optionally as its hydrochloride or lactate salt) and trihexyphenidyl (benzhexol) hydrochloride, COMT inhibitors such as entacapone, MOA-B inhibitors, antioxidants, A2a adenosine receptor antagonists, cholinergic agonists, MDA receptor antagonists, serotonin receptor antagonists and dopamine receptor agonists such as alentemol, bromocriptine, fenoldopam, lisuride, naxagolide, pergolide and pramipexole. It will be appreciated that the dopamine agonist may be in the form of a pharmaceutically acceptable salt, for example, alentemol hydrobromide, bromocriptine mesylate, fenoldopam mesylate, naxagolide hydrochloride and pergolide mesylate.

In another embodiment, the subject compound may be employed in combination with a compound from the phenothiazine, thioxanthene, heterocyclic dibenzazepine, butyrophenone, diphenylbutylpiperidine and indolone classes of neuroleptic agent. Suitable examples of phenothiazines include chlorpromazine, mesoridazine, thioridazine, acetophenazine,

fluphenazine, perphenazine and trifluoperazine. Suitable examples of thioxanthenes include chlorprothixene and thiothixene. An example of a dibenzazepine is clozapine. An example of a butyrophenone is haloperidol. An example of a diphenylbutylpiperidine is pimozide. An example of an indolone is molindolone. Other neuroleptic agents include loxapine, sulpiride and risperidone. It will be appreciated that the neuroleptic agents when used in combination with the subject compound may be in the form of a pharmaceutically acceptable salt, for example, chlorpromazine hydrochloride, mesoridazine besylate, thioridazine hydrochloride,

acetophenazine maleate, fluphenazine hydrochloride, flurphenazine enathate, fluphenazine decanoate, trifluoperazine hydrochloride, thiothixene hydrochloride, haloperidol decanoate, loxapine succinate and molindone hydrochloride. Perphenazine, chlorprothixene, clozapine, haloperidol, pimozide and risperidone are commonly used in a non-salt form. Thus, the subject compound may be employed in combination with acetophenazine, alentemol, aripiprazole, amisuipride, benzhexol, bromocriptine, biperiden, chlorpromazine, chlorprothixene, clozapine, diazepam, fenoldopam, fluphenazine, haloperidol, levodopa, levodopa with benserazide, levodopa with carbidopa, lisuride, loxapine, mesoridazine, molindolone, naxagolide, olanzapine, pergolide, perphenazine, pimozide, pramipexole, quetiapine, risperidone, sulpiride,

tetrabenazine, frihexyphenidyl, thioridazine, thiothixene, trifluoperazine or ziprasidone.

Examples of combinations of the compounds include combinations with agents for the treatment of pain, for example non-steroidal anti-inflammatory agents, such as aspirin, diclofenac, duflunisal, fenoprofen, flurbiprofen, ibuprofen, indomethacin, ketoprofen, ketorolac, naproxen, oxaprozin, piroxicam, sulindac and tolmetin; COX-2 inhibitors, such as celecoxib, rofecoxib, valdecoxib, 406381 and 644784; CB-2 agonists, such as 842166 and SAB378; VR-1 antagonists, such as AMG517, 705498, 782443, PAC20030, VI 14380 and A425619; bradykinin B 1 receptor antagonists, such as SSR240612 and NVPSAA164; sodium channel blockers and antagonists, such as VX409 and SPI860; nitric oxide synthase (NOS) inhibitors (including iNOS and nNOS inhibitors), such as SD6010 and 274150; glycine site antagonists, including lacosamide; neuronal nicotinic agonists, such as ABT 894; NMDA antagonists, such as

AZD4282; potassium channel openers; AMPA/kainate receptor antagonists; calcium channel blockers, such as ziconotide and NMED160; GABA-A receptor IO modulators (e.g., a GABA- A receptor agonist); matrix metalloprotease (MMP) inhibitors; thrombolytic agents; opioid analgesics such as codeine, fentanyl, hydromorphone, levorphanol, meperidine, methadone, morphine, oxycodone, oxymorphone, pentazocine, propoxyphene; neutrophil inhibitory factor (NIF); pramipexole, ropinirole; anticholinergics; amantadine; monoamine oxidase B15 ("MAO- B") inhibitors; 5HT receptor agonists or antagonists; mGlu5 antagonists, such as AZD9272; alpha agonists, such as AGNXX/YY; neuronal nicotinic agonists, such as ABT894; MDA receptor agonists or antagonists, such as AZD4282; KI antagonists; selective serotonin reuptake inhibitors ("SSRI") and/or selective serotonin and norepinephrine reuptake inhibitors ("SS RI"), such as duloxetine; tricyclic antidepressant drugs, norepinephrine modulators;

lithium; valproate; gabapentin; pregabalin; rizatriptan; zolmitriptan; naratriptan and sumatriptan.

The compounds of the present invention may be administered in combination with compounds useful for enhancing sleep quality and preventing and treating sleep disorders and sleep disturbances, including e.g., sedatives, hypnotics, anxiolytics, antipsychotics, antianxiety agents, antihistamines, benzodiazepines, barbiturates, cyclopyrrolones, orexin antagonists, alpha- 1 antagonists, GAB A agonists, 5HT-2 antagonists including 5HT-2A antagonists and 5HT- 2A/2C antagonists, histamine antagonists including histamine H3 antagonists, histamine H3 inverse agonists, imidazopyridines, minor tranquilizers, melatonin agonists and antagonists, melatonergic agents, other orexin antagonists, orexin agonists, prokineticin agonists and antagonists, pyrazolopyrimidines, T-type calcium channel antagonists, triazolopyridines, and the like, such as: adinazolam, allobarbital, alonimid, alprazolam, amitriptyline, amobarbital, amoxapine, armodafinil, APD-125, bentazepam, benzoctamine, brotizolam, bupropion, busprione, butabarbital, butalbital, capromorelin, capuride, carbocloral, chloral betaine, chloral hydrate, chlordiazepoxide, clomipramine, clonazepam, cloperidone, clorazepate, clorethate, clozapine, conazepam, cyprazepam, desipramine, dexclamol, diazepam, dichloralphenazone, divalproex, diphenhydramine, doxepin, EMD-281014, eplivanserin, estazolam, eszopiclone, ethchlorynol, etomidate, fenobam, flunitrazepam, flurazepam, fluvoxamine, fluoxetine, fosazepam, gaboxadol, glutethimide, halazepam, hydroxyzine, ibutamoren, imipramine, indiplon, lithium, lorazepam, lormetazepam, LY-156735, maprotiline, MDL-100907, mecloqualone, melatonin, mephobarbital, meprobamate, methaqualone, methyprylon, midaflur, midazolam, modafinil, nefazodone, NGD-2-73, nisobamate, nitrazepam, nortriptyline, oxazepam, paraldehyde, paroxetine, pentobarbital, perlapine, perphenazine, phenelzine, phenobarbital, prazepam, promethazine, propofol, protriptyline, quazepam, ramelteon, reclazepam, roletamide, secobarbital, sertraline, suproclone, TAK-375, temazepam, thioridazine, tiagabine, tracazolate, tranylcypromaine, trazodone, triazolam, trepipam, tricetamide, triclofos, trifluoperazine, trimetozine, trimipramine, uldazepam, venlafaxine, zaleplon, zolazepam, zopiclone, Zolpidem, and salts thereof, and combinations thereof, and the like, or the compound of the present invention may be administered in conjunction with the use of physical methods such as with light therapy or electrical stimulation.

The subject or patient to whom the compounds of the present invention is administered is generally a human being, male or female, in whom Ml allosteric modulation is is desired, but may also encompass other mammals, such as dogs, cats, mice, rats, cattle, horses, sheep, rabbits, monkeys, chimpanzees or other apes or primates, for which treatment of the above noted disorders is desired.

The term "composition" as used herein is intended to encompass a product comprising specified ingredients in predetermined amounts or proportions, as well as any product which results, directly or indirectly, from combination of the specified ingredients in the specified amounts. This term in relation to pharmaceutical compositions is intended to encompass a product comprising one or more active ingredients, and an optional carrier comprising inert ingredients, as well as any product which results, directly or indirectly, from combination, complexation or aggregation of any two or more of the ingredients, or from dissociation of one or more of the ingredients, or from other types of reactions or interactions of one or more of the ingredients.

In general, pharmaceutical compositions are prepared by uniformly and intimately bringing the active ingredient into association with a liquid carrier or a finely divided solid carrier or both, and then, if necessary, shaping the product into the desired formulation. In the pharmaceutical composition the active compound, which is a compound of formula (I) is included in an amount sufficient to produce the desired effect upon the process or condition of diseases. Accordingly, the pharmaceutical compositions of the present invention encompass any composition made by admixing a compound of the present invention and a pharmaceutically acceptable carrier.

The carrier may take a wide variety of forms depending on the form of preparation desired for administration, e.g., oral or parenteral (including intravenous). Thus, the

pharmaceutical compositions of the present invention can be presented as discrete units suitable for oral administration such as capsules, cachets or tablets each containing a predetermined amount of the active ingredient. Further, the compositions can be presented as a powder, as granules, as a solution, as a suspension in an aqueous liquid, as a non-aqueous liquid, as an oil- in-water emulsion or as a water-in-oil liquid emulsion. In addition to the common dosage forms set out above, the compounds of the invention, or pharmaceutically acceptable salts thereof, may also be administered by controlled release means and/or delivery devices.

Pharmaceutical compositions intended for oral use may be prepared according to any method known to the art for the manufacture of pharmaceutical compositions and such compositions may contain one or more agents selected from the group consisting of sweetening agents, flavoring agents, coloring agents and preserving agents in order to provide pharmaceutically elegant and palatable preparations. Tablets may contain the active ingredient in admixture with non-toxic pharmaceutically acceptable excipients which are suitable for the manufacture of tablets. These excipients may be, for example, inert diluents, such as calcium carbonate, sodium carbonate, lactose, calcium phosphate or sodium phosphate; granulating and disintegrating agents, for example, corn starch, or alginic acid; binding agents, for example starch, gelatin or acacia, and lubricating agents, for example magnesium stearate, stearic acid or talc. The tablets may be uncoated or they may be coated by known techniques to delay disintegration and absorption in the gastrointestinal tract and thereby provide a sustained action over a longer period.

A tablet containing the composition of this invention may be prepared by compression or molding, optionally with one or more accessory ingredients or adjuvants. Compressed tablets may be prepared by compressing, in a suitable machine, the active ingredient in a free-flowing form such as powder or granules, optionally mixed with a binder, lubricant, inert diluent, surface active or dispersing agent. Molded tablets may be made by molding in a suitable machine, a mixture of the powdered compound moistened with an inert liquid diluent. Each tablet preferably contains from about 0.1 mg to about 500 mg of the active ingredient and each cachet or capsule preferably containing from about 0.1 mg to about 500 mg of the active ingredient.

Compositions for oral use may also be presented as hard gelatin capsules wherein the active ingredient is mixed with an inert solid diluent, for example, calcium carbonate, calcium phosphate or kaolin, or as soft gelatin capsules wherein the active ingredient is mixed with water or an oil medium, for example peanut oil, liquid paraffin, or olive oil.

Other pharmaceutical compositions include aqueous suspensions, which contain the active materials in admixture with excipients suitable for the manufacture of aqueous

suspensions. In addition, oily suspensions may be formulated by suspending the active ingredient in a vegetable oil, for example arachis oil, olive oil, sesame oil or coconut oil, or in a mineral oil such as liquid paraffin. Oily suspensions may also contain various excipients. The pharmaceutical compositions of the invention may also be in the form of oil-in-water emulsions, which may also contain excipients such as sweetening and flavoring agents.

The pharmaceutical compositions may be in the form of a sterile injectable aqueous or oleaginous suspension, or in the form of sterile powders for the extemporaneous preparation of such sterile injectable solutions or dispersions. In all cases, the final injectable form must be sterile and must be effectively fluid for easy syringability. The pharmaceutical compositions must be stable under the conditions of manufacture and storage; thus, preferably should be preserved against the contaminating action of microorganisms such as bacteria and fungi.

Pharmaceutical compositions of the present invention can be in a form suitable for topical use such as, for example, an aerosol, cream, ointment, lotion, dusting powder, or the like.

Further, the compositions can be in a form suitable for use in transdermal devices. These formulations may be prepared via conventional processing methods. As an example, a cream or ointment is prepared by mixing hydrophilic material and water, together with about 5 wt% to about 10 wt% of the compound, to produce a cream or ointment having a desired consistency.

Pharmaceutical compositions of this invention can also be in a form suitable for rectal administration wherein the carrier is a solid. It is preferable that the mixture forms unit dose suppositories. Suitable carriers include cocoa butter and other materials commonly used in the art.

By "pharmaceutically acceptable" it is meant the carrier, diluent or excipient must be compatible with the other ingredients of the formulation and not deleterious to the recipient thereof.

The terms "administration of or "administering a" compound should be understood to mean providing a compound of the invention to the individual in need of treatment in a form that can be introduced into that individual's body in a therapeutically useful form and therapeutically useful amount, including, but not limited to: oral dosage forms, such as tablets, capsules, syrups, suspensions, and the like; injectable dosage forms, such as IV, EVI, or IP, and the like;

transdermal dosage forms, including creams, jellies, powders, or patches; buccal dosage forms; inhalation powders, sprays, suspensions, and the like; and rectal suppositories.

The term "therapeutically effective amount" as used herein, refers to an amount of the compound of Formula (I) and/or an additional therapeutic agent, or a composition thereof that is effective in producing the desired therapeutic, ameliorative, inhibitory or preventative effect when administered to a patient suffering from a disease or disorder mediated by the muscarinic Ml receptor. In the combination therapies of the present invention, a therapeutically effective amount can refer to each individual agent or to the combination as a whole, wherein the amounts of all agents administered are together effective, but wherein the component agent of the combination may not be present individually in an effective amount.

The term "preventing," as used herein with respect to a disease or disorder mediated by the muscarinic Ml receptor, refers to reducing the likelihood of the occurrence of the disease or condition.

As used herein, the term "treatment" or "treating" means any administration of a compound of the present invention and includes (1) inhibiting the disease in an animal that is experiencing or displaying the pathology or symptomatology of the diseased (i.e., arresting further development of the pathology and/or symptomatology), or (2) ameliorating the disease in an animal that is experiencing or displaying the pathology or symptomatology of the diseased (i.e., reversing the pathology and/or symptomatology). The compositions containing compounds of the present invention may conveniently be presented in unit dosage form and may be prepared by any of the methods well known in the art of pharmacy. The term "unit dosage form" is taken to mean a single dose wherein all active and inactive ingredients are combined in a suitable system, such that the patient or person

administering the drug to the patient can open a single container or package with the entire dose contained therein, and does not have to mix any components together from two or more containers or packages. Typical examples of unit dosage forms are tablets or capsules for oral administration, single dose vials for injection, or suppositories for rectal administration. This list of unit dosage forms is not intended to be limiting in any way, but merely to represent typical examples of unit dosage forms.

The compositions containing compounds of the present invention may conveniently be presented as a kit, whereby two or more components, which may be active or inactive ingredients, carriers, diluents, and the like, are provided with instructions for preparation of the actual dosage form by the patient or person administering the drug to the patient. Such kits may be provided with all necessary materials and ingredients contained therein, or they may contain instructions for using or making materials or components that must be obtained independently by the patient or person administering the drug to the patient.

When treating or ameliorating a disorder or disease for which compounds of the present invention are indicated, generally satisfactory results are obtained when the compounds of the present invention are administered at a daily dosage of from about 0.1 mg to about 100 mg per kg of animal body weight, preferably given as a single daily dose or in divided doses two to six times a day, or in sustained release form. The total daily dosage is from about 1.0 mg to about 2000 mg, preferably from about 0.1 mg to about 20 mg per kg of body weight. In the case of a 70 kg adult human, the total daily dose will generally be from about 7 mg to about 1,400 mg. This dosage regimen may be adjusted to provide the optimal therapeutic response. The compounds may be administered on a regimen of 1 to 4 times per day, preferably once or twice per day.

The amount of active ingredient that may be combined with the carrier materials to produce a single dosage form will vary depending upon the host treated and the particular mode of administration. For example, a formulation intended for the oral administration to humans may conveniently contain from about 0.005 mg to about 2.5 g of active agent, compounded with an appropriate and convenient amount of carrier material. Unit dosage forms will generally contain between from about 0.005 mg to about 1000 mg of the active ingredient, typically 0.005, 0.01 mg, 0.05 mg, 0.25 mg, 1 mg, 5 mg, 25 mg, 50 mg, 100 mg, 200 mg, 300 mg, 400 mg, 500 mg, 600 mg, 800 mg or 1000 mg, administered once, twice or three times a day. It will be understood, however, that the specific dose level and frequency of dosage for any particular patient may be varied and will depend upon a variety of factors including the activity of the specific compound employed, the metabolic stability and length of action of that compound, the age, body weight, general health, sex, diet, mode and time of administration, rate of excretion, drug combination, the severity of the particular condition, and the host undergoing therapy.

The following abbreviations are used throughout the text:

AcOH acetic acid

MeOH: methanol

CbZ-Cl benzyl chloroformate

CH₂C1₂ dichloromethane

EtOH: ethanol

DMAP 4-N,N-dimethylaminopyridine

DMF: dimethylformamide

DMSO: dimethylsulfoxide

TBDMSC1: fert-butyldimethylsilyl chloride

THF: tetrahydrofuran

K₂C0₃ : potassium carbonate

Pd/C: palladium on carbon

MeCN: acetonitrile

NaOH: sodium hydroxide

Ac: acetyl

DCM: dichloromethane

w-CPBA: meta-chloroperoxybenzoic acid

DMEM: Dulbecco's Modified Eagle Medium (High Glucose)

FBS: fetal bovine serum

rt: room temperature

aq: aqueous

HPLC: high performance liquid chromatography

MS: mass spectrometry

mM: milimolar

nM: nanomolar

μΜ: micromolar General Experimental Comments

All reactions were stirred (mechanically, stir bar/stir plate, or shaken) and conducted under an inert atmosphere of nitrogen or argon unless specifically stated otherwise and all solvents were anhydrous unless otherwise specified. The progress of reactions was determined by either analytical thin layer chromatography (TLC) performed with E. Merck (EMD Millipore, Billerica MA) precoated TLC plates, silica gel 60F-254, layer thickness 0.25 mm or liquid chromatography-mass spectrum (LC-MS). Mass analysis was performed on an Agilentl200 Series coupled with Agilent 6130 Quadrupole LC VIS with ES+APCI (positive/negative) mode. High performance liquid chromatography (HPLC) was conducted on an Agilent 1200 series HPLC on ATLANTIS dC18(250x4.6m-5 μ) column with gradient 10:90-100 v/v

CH₃CN/H₂0 + v 0.1 % TFA in water; flow rate 1.0 mL/min, UV wavelength 215

nm). Concentration of solutions was carried out on a rotary evaporator under reduced pressure. Flash chromatography was performed by Biotage-Isolera TM Flash chromatography instrument on Biotage® SNAP KP-Sil pre packed with 50 μπι silica particles with a surface area of 500 m²/g. lH-NMR spectra were obtained on a 400 BRUKER Avance ® Spectrometer in CDCI3 or CD3OD or other solvents as indicated and chemical shifts are reported as δ using the solvent peak as reference and coupling constants are reported in hertz (Hz).

Starting materials useful for the preparation of the compounds in the present invention are known in the art or may be prepared using chemical methodologies known to those skilled in the art.

Example 1

Scheme 1

Scheme I (cont.)

Step 1: Methyl l,2,3.,4-tetrahvdroquinoxaline-2-carboxylate (1-b)

To a stirred solution of methyl quinoxaline-2-carboxylate (1 -a) (4.0 g, 21 mmol) in ethanol (50 mL) was added acetic acid (1.2 mL, 21 mmol) and Pd/C (10 wt%, 2.2 g, 21 mmol). The solution was degassed and then stirred under 5 kg pressure of hydrogen for 36 hours. The mixture was filtered through CELITE (diatomaceous earth) bed and the CELITE bed was washed with excess methanol. The combined filtrate was concentrated under reduced pressure and the mixture was purified by column chromatography (25 - 50% ethyl acetate in petroleum ether) to provide the titled compound (1-b), which gave a proton NMR spectra consistent with theory a mass ion [ES+] of 193.2 for [M + H]⁺.

Step 2: 1-benzyl 3-methyl 3,4-dihydroquinoxaline-l,3f2H)-dicarboxylate (1-c) To a stirred solution of methyl l,2,3,4-tetrahydroquinoxaline-2-carboxylate (1-b) (50 mg, 0.26 mmol) in acetonitrile (1 mL) under nitrogen at 0 °C was added K₂C0₃ (54 mg, 0.39 mmol) followed by benzyl chloroformate (0.037 mL, 0.260 mmol). The resultant solution was stirred for 3 hours at room temperature and then diluted with water and extracted with

ethylacetate (3 x 5 mL). The combined organic layers were washed with brine, dried with sodium sulfate, filtered and concentrated in vacuo. The residue was purified by silica gel column chromatography (20 - 25% gradient ethyl acetate in petroleum ether) to provide the titled compound (1 -c), which gave a proton NMR spectra consistent with theory and a mass ion consistent with theory, [ES+] 327.0 for [M + H]⁺.

Step 3: l-benzyl-3-methyl-4-f2-chloroacetyl)-3,4-dihydroquinoxaline-l,3f2H)

dicarboxylate (1-d)

To a stirred solution of 1 -benzyl 3-methyl 3,4-dihydroquinoxaline-l,3(2H)-dicarboxylate (1-c) (500 mg, 1.53 mmol) in dichloromethane (20 mL) at 0 °C under nitrogen was added triethylamine (465 mg, 4.60 mmol), DMAP (catalytic) followed by chloroacetyl chloride (260 mg, 2.29 mmol). The resultant solution was stirred for 4 hours at room temperature and then diluted with water (100 mL) and extracted with dichlorom ethane (3 x 30 mL). The combined organic extracts were washed with brine, dried with sodium sulfate and concentrated in vacuo. The residue was purified by silica gel column chromatography (20 - 25% ethyl acetate in petroleum ether) to provide the title compound (1-d) that gave a mass ion consistent with theory, [ES+] of 403.4 for [M + H]⁺.

Step 4: benzyl 3-^lS,2S)-2-hvdroxycvclohexyl)-l,4-dioxo-l,2,3.,4,4 ,5-hexahvdro-6H- pyrazino[l,2- lquinoxaline-6-carboxylate (1-e) To a solution of 1-benzyl 3-methyl 4-(2-chloroacetyl)-3,4-dihydroquinoxaline-l,3(2H)- dicarboxylate (1-d) (450 mg, 1.12 mmol) and (l^^^-aminocyclohexanol (193 mg, 1.67 mmol) in THF (30 mL) at 0 °C was added potassium carbonate (309 mg, 2.23 mmol). The mixture was stirred at room temperature for 16 hours and then refluxed for 16 hours. The mixture was cooled to room temperature, poured into water and then extracted with ethyl acetate. The combined organic layers were dried with sodium sulfate and then concentrated in vacuo. The residue was purified by silica gel column chromatography (60% ethyl acetate in petroleum ether) to provide the titled compound (1-e) (as mixture of diasteromers) that gave a mass ion consistent with theory, [ES+] of 450.2 for [M + H]⁺.

Step 5: Benzyl 3-( ( lS S)-2-( ( fe^butyldimethylsilvDoxyfcvclohexyD- 1 ,4-dioxo- l,2,3.,4,4 ,5-hexahvdro-6H-pyrazino[l,2- lquinoxaline-6-carboxylate (1-f)

To a solution of benzyl 3-((l,S',2₎S)-2-hydroxycyclohexyl)-l,4-dioxo-l,2,3,4,4a,5- hexahydro-6H-pyrazino[l,2-a]quinoxaline-6-carboxylate (1-e) (380 mg, 0.845 mmol) and imidazole (230 mg, 3.38 mmol) in DMF (10 mL) at 0 °C was added TBDMSC1 (319 mg, 2.11 mmol). The mixture was stirred at room temperature for 16 hours and then poured into ice cold water, which was extracted with ethyl acetate. Then combined organic layer was washed with brine, dried with sodium sulfate and then concentrated in vacuo. The residue was purified by silica gel column chromatography (50% ethyl acetate in petroleum ether) to provide the titled (1- f) compound that gave a proton MR spectra consistent with theory and a mass ion [ES+] of 564.4 for [M + H]⁺. Step 6: 3-faS,2S)-2- fe^-butyldimethylsilvnoxy)cvclohexyn-2,3,5,6-tetrahvdro-lH- Pyrazino[l,2- lquinoxaline-l,4f4 -H)-dione (1-g) To a solution of benzyl 3-((l,S',2₎S)-2-((tert-butyldimethylsilyl)oxy)cyclohexyl)-l,4- dioxo-l,2,3,4,4a,5-hexahydro-6H-pyrazino[l,2-a]quinoxaline-6-carboxylate (1-f) (400 mg, 0.710 mmol) in MeOH (20 mL) was added Pd/C (10 wt%, 120 mg, 1.128 mmol). The reaction flask was sparged under hydrogen (1 atm). The resulting mixture was stirred at room temperature for 4 hours. The mixture was sparged with nitrogen, filtered through a CELITE bed and then the CELITE bed was washed with a 1 : 1 mixture of dichlorom ethane : methanol. The filtrate was concentrated in vacuo to provide the titled compound (1-g) that gave a proton MR spectra consistent with theory and a mass ion [ES+] of 430.4 for [M + H]⁺.

Step 7: 3-faS,2S)-2- fe^-butyldimethylsilvnoxy)cvclohexyn-6-q6-methylpyridin-3- yl)methyl)-2,3.,5,6-tetrahvdro-lH-pyrazino[l,2- lquinoxaline-l,4f4 -H)-dione

To a solution of 3-((l,S',2₎S)-2-((tert-butyldimethylsilyl)oxy)cyclohexyl)-2,3,5,6- tetrahydro-lH-pyrazino[l,2-a]quinoxaline-l,4(4a-H)-dione (1-g) (100 mg, 0.233 mmol) in DMF (5 mL) at room temperature was added potassium carbonate (129 mg, 0.93 1 mmol). The mixture was stirred for 10 minutes and was then treated with 5-(bromomethyl)-2-methylpyridine (65.0 mg, 0.349 mmol) followed by sodium iodide (34.9 mg, 0.233 mmol). The mixture was stirred for 16 hours at ambient temperature and then poured into ice water and extracted with ethyl acetate. The combined organic layers were washed with brine, dried with sodium sulfate and then concentrated in vacuo. The residue was taken on as is without further purification. Step 8: 3-( ( lS,2S)-2-hvdroxycvclohexyn-6-( ( 6-methylpyridin-3-vnmethvn-2,3,5,6- tetrahydro-lH-pyrazino[l,2-alquinoxaline-l,4f4 H)-dione (1-1)

To a solution of 3-((l,S',2₎S)-2-((tert-butyldimethylsilyl)oxy)cyclohexyl)-6-((6- methylpyridin-3-yl)methyl)-2,3,5,6 etrahydro-lH-pyrazino[l,2-a]quinoxaline-l,4(4aH)-dione (1-h) (100 mg, 0.187 mmol) in methanol (5 mL) at 0 °C was added HC1 in dioxane (5.0 mL, 20 mmol). The mixture was stirred at room temperature for 3 hours, concentrated in vacuo, and the residue was purified by reverse phase preparative HPLC (90: 10 to 0: 100; water containing 0.1% formic acid : acetonitrile containing 0.1% formic acid) to provide the titled compound (1 -1) as a mixture of diasteromers/H MR (400MHz, CD₃OD): δ. 8.36 (s, 1H), 7.78 (dd, J = 1.6, 8.0 Hz, 1H), 7.71-7.68 (m, 1H), 7.29 (d, J = 8.0 Hz, 1H), 7.07-7.02 (m, 1H), 6.83-6.80 (m, 1H), 6.75- 6.70 (m, 1H), 4.70-4.65 (m, 1H), 4.59-4.52 (m, 2H), 4.30-4.25 (m, 1H), 4.13-4.08 (m, 2H), 3.87-3.82 (m, 1H), 3.75-3.67 (m, 3H), 2.52 (s, 3H), 2.12-2.02 (m, 1H), 1.78-1.64 (m, 4H), 1.43-1.27 (m, 3H) ppm; LRMS calculated (M+H)⁺ C24H29N4O3 [calc'd 421.2, obs. 421.4].

Biological Assays The utility of the compounds as Ml receptor positive allosteric modulators may be demonstrated by methodology known in the art including by the assay described below. The assay is designed to select compounds that possess modulator activity at the acetylcholine muscarinic Ml receptor or other muscarinic receptors expressed in CHOnfat cells by measuring the intracellular calcium with a FLIPR384 Fluorometric Imaging Plate Reader System. The assay studies the effect of one or several concentrations of test compounds on basal or acetylcholine-stimulated Ca2+ levels using FLIPR.

For each compound of the invention that was evaluated, the compound was prepared and subjected to a pre-incubation period of four minutes. Thereafter, a single EC20 concentration of acetylcholine was added to each well (3 nM final). The intracellular Ca2+ level of each sample was measured and compared to an acetylcholine control to determine any modulatory activity.

Cells: CHOnfat/hMl, hM2, hM3 or hM4 cells were plated 24 hours before the assay at a density of 18,000 cells/well (100 L) in a 384 well plate. CHOnfat/hMl and CHOnfat/hM3 Growth Medium: 90% DMEM (Hi Glucose); 10% HI FBS; 2 mM L-glutamine; 0.1 mM NEAA; Pen-Strep; and lmg/ml Geneticin, were added. For M2Gqi 5 CHOnfat and M4Gqi5CHOnfat cells, an additional 600 μg/ml hygromycin was added.

Equipment: 384 well plate, 120 μΕ addition plate; 96-well Whatman 2 ml Uniplate Incubator, 37 °C, 5% CO2; Skatron EMBLA-384 Plate Washer; Multimek Pipetting System; Genesis Freedom 200 System; Mosquito System; Temo Nanolitre Pipetting System; and

FLIPR384 Fluorometric Imaging Plate Reader System were used.

Buffers: Assay Buffer: Hanks Balanced Salt Solution, with 20 mM Hepes, 2.5 mM

Probenecid (Sigma P-8761) first dissolved in 1 N NaOH, 1% Bovine Serum Albumin (Sigma A- 9647). Dye Loading Buffer: Assay Buffer plus 1% Fetal Bovine Serum and Fluo-4AM/Pluronic Acid Mixture. 2 mM Fluo-4AM ester stock in DMSO (Molecular Probes F- 14202)

Concentration of 2 μΜ in buffer for a final concentration of ΙμΜ in Assay. 20% Pluronic acid solution stock, with a concentration of 0.04% in Buffer, 0.02% in Assay. 65 μΕ of 2 mM Fluo- 4AM were mixed with 130 μL· of 20% pluronic acid. The resulting solution and 650 μL· FBS was added to the assay buffer for a total volume of 65 mL.

Positive Controls: 4-Br-A23187: 10 mM in DMSO, final concentration 10 μΜ.

Acetylcholine: 10 μΜ in water, working stock at both 20 μΜ and 30 μΜ in assay buffer, final concentration of 10 μΜ. This was used to check the maximum stimulation of the CHOKl/hMl cells. 20 μΜ (2x) acetylcholine was added in the preincubation part of the assay, and the 30 μΜ (3x) stock is added in the second part. (EC20)Acetyl choline: 10 mM in water, working stock of 9 nM (3x), and final concentration in assay was 3 nM. This was used after the preincubation with test compounds. Addition of the EC20 Acetylcholine to each well with a test compound will ascertain any modulator activity. 24 wells contained 3nM Acetylcholine alone as a control.

Screening Plate: Compounds were titrated in 96-well plates (columns 2-11), 100% DMSO, started at a concentration of 15 mM (150x stock concentration), and 3-fold serial dilutions using Genesis Freedom200 System. Four 96-well plates were combined into a 384- well plate using Mosquito Nanolitre Pipetting System by transferring 1 μΐ of serial diluted compounds to each well, and 1 mM acetylcholine (lOOx stock concentration) were added as a control. Using Temo, 49 μΐ assay buffer was added to each well of the 384-well plate right before assay.

In a 96-well Whatman 2ml Uniplate, 9 nM Acetylcholine (3x) is pipetted into wells corresponding to the screening compounds, and into control wells. The 30 μΜ acetylcholine control (3x) was added into control wells, and the 3x agonist plate was transferred into a 384 well plate.

Cells were washed three times with 100 μΐ. of buffer, leaving 30μΙ. of buffer in each well. Using Multimek, 30 μΐ. of Dye Loading Buffer was added into each well and incubated at 37 °C, 5% CO2 for up to one hour.

After 60 minutes, the cells were washed three times with 100 μΐ. of buffer, leaving 30 μΐ. of buffer in each well. The cell plate, screening plate, and agonist addition plates were placed on the platform in the FLIPR and the door closed. A signal test to check background fluorescence and basal fluorescence signal was performed. Laser intensity was adjusted if necessary.

Four minutes of pre-incubation with the test compounds was provided to determine any agonist activity on the Ml receptor by comparison to the 1 mM acetylcholine control. After preincubation, the EC20 value of acetylcholine (3 nM final) was added to determine any modulator activity. A further description of the muscarinic FLIPR assay can be found in Conn et al., PCT/US2004/004735, which published as WO 2004/073639.

In particular, the compounds of the following examples had activity in the

aforementioned assay, generally with an IP (inflection point) of 10 μΜ (10,000 nM) or less. The inflection point was calculated from the FLIPR values, and was a measure of activity. Such a result was indicative of the intrinsic activity of the compounds in use as Ml allosteric modulators. IP values from the aforementioned assay for representative exemplary compounds of the invention (as described herein) are provided below in Table 1 below:

While the invention has been described and illustrated with reference to certain particular embodiments thereof, those skilled in the art will appreciate that various adaptations, changes, modifications, substitutions, deletions, or additions of procedures and protocols may be made without departing from the spirit and scope of the invention. It is intended, therefore, that the invention be defined by the scope of the claims that follow and that such claims be interpreted as broadly as is reasonable.

Claims

claimed is:

1. Compound of formula (I)

or a pharmaceutically acceptable salt thereof, wherein w is 2, 3, 4, 5, or 6;

V is CH₂, or

one or two of V is S, N, or O, and the others are CH₂; X, Y, Q, and Z are each CR³, or one or two of X, Y, Q and Z is N and the others are CR^¾; p is 0, 1, 2, or 3;

R³ is hydrogen, halogen, -C1.4 alkyl, -S(Ci -6 alkyl), or hyd

R¹ is selected from

hydrogen,

aryl,

heteroaryl,

halogen,

-CN,

-O-C i-6 alkyl,

-Ci-6 alkyl, -C2-6 alkenyl,

-S(Ci-6 alkyl),

-S(=0)_n-R⁴, and

- R⁵R⁶,

halogen,

hydroxy,

-O-Ci-6 alkyl,

-C i-6 alkyl,

-C(=0)-(0)_m-R⁷,

-NR⁵R⁶,

-S(Ci-6 alkyl),

-S(=0)_n-R⁴, and

oxo;

each m is 0 or 1;

each n is 0, 1, or 2;

each R² is independently selected from

halogen,

hydroxy,

-O-C i -6 alkyl,

-Ci-6 alkyl,

-S(Ci_6 alkyl),

-S(=0)_n-R⁴,

-C2-6 alkenyl, -CN,

-C(=0)-(0)_m-R⁷,

- R⁵R⁶,

oxo,

aryl,

heteroaryl, and

heterocycloalkyl,

halogen,

hydroxy,

-S(Ci-6 alkyl),

-O-Ci-6 alkyl, and

-Ci-6 alkyl; R⁴ and R⁷ are each independently selected from

hydrogen, -Ci -6 alkyl, and -(CH₂)_n-aryl,

halogen,

cyano,

hydrogen, -Ci-6 alkyl, -C3-6 cycloalkyl, -C(=0)-(0)m-R⁸, -S(=0)_n-R⁸, wherein R⁸ are each independently selected from

hydrogen,

-Ci-6 alkyl, and -(CH₂)_n-aryl,

2. A compound of claim 1, or a pharmaceutically acceptable salt thereof, wherein R¹ is selected from hydrogen, aryl, heteroaryl, halogen, -CN, -O-Ci-6 alkyl, -Ci-6 alkyl, -C2-6 alkenyl, -S(Ci -6 alkyl), -S(=0)_n-R⁴, and -NR⁵R⁶, wherein said aryl, heteroaryl, alkyl, and alkenyl moiety is substituted with 0, 1, 2, or 3 groups selected from halogen, hydroxy, -O-Ci -6 alkyl, -Ci-6 alkyl, -C(=0)-(0)_m-R⁷, -NR⁵R⁶,-S(Ci-6 alkyl), and oxo.

3. A compound of claim 2, or a pharmaceutically acceptable salt thereof, wherein R¹ is selected from aryl, -Ci-6 alkyl, and hetoroaryl, wherein said aryl, alkyl, and heteroaryl is substituted with 0, 1, 2 or 3 groups selected from halogen, hydroxy, -O-Ci -6 alkyl, -Ci -6 alkyl, - -S(Ci-6 alkyl), and oxo.

4. A compound of claim 3, or a pharmaceutically acceptable salt thereof, wherein each R² is independently selected from halogen, hydroxy, -O-Ci-6 alkyl, -Ci-6 alkyl, -C2-6 alkenyl, -CN, -NR⁵R⁶, aryl, -S(Ci _6 alkyl), heteroaryl, and heterocycloalkyl, wherein said aryl, heteroaryl, alkyl, and heterocycloalkyl, moiety is substituted with 0, 1, 2, or 3 groups selected from halogen, hydroxy, -S(Ci -6 alkyl), -O-Ci -6 alkyl, and -Ci -6 alkyl.

5. A compound of claim 4 or a pharmaceutically acceptable salt thereof, wherein each R² is independently selected from halogen, -O-C 1.3 alkyl, -S(Ci -6 alkyl), and -Ci-3 alkyl, wherein said alkyl moiety is substituted with 0, 1, 2, or 3 groups selected from halogen, hydroxy, -S(C i -6 alkyl), -O-C3.6 alkyl, and -C 1 -6 alkyl.

6. A compound of claim 5 or a pharmaceutically acceptable salt thereof, wherein Rl is -Ci-6 alkyl substituted with 0, 1, 2, or 3 groups selected from fluoro, chloro, hydroxy, methoxy, ethoxy, thiom ethyl, thioethyl, and thiopropyl.

7. A compound of claim 6 or a pharmaceutically acceptable salt thereof, wherein p is O, 1 or 2.

8. A compound of claim 7 or a pharmaceutically acceptable salt thereof, wherein p is O.

9. A compound of claim 8 or a pharmaceutically acceptable salt thereof, wherein V is CH₂, or one or two of V is N and the other are CH₂.

10. A compound of claim 9 or a pharmaceutically acceptable salt thereof, wherein w is 3, 4, 5, or 6.

11. A compound of claim 1 or a pharmaceutically acceptable salt thereof, wherein X, Y, Q, and Z are each CR^a.

12. A compound of claim 1 or a pharmaceutically acceptable salt thereof, wherein one or two of X, Y, Q and Z is N and the others are CR^a.

13. A compound of claim 1 selected from:

3-((l,S',2₎S)-2-hydroxycyclohexyl)-6-((6-methylpyridin-3-yl)methyl)-2,3,5,6-tetrahydro-lH- pyrazino[ 1 ,2-a]quinoxaline- 1 ,4(4aH)-dione; and 3-((lR,2R)-2-hydroxycyclohexyl)-6-((6-methylpyridin-3-yl)methyl)-2,3,5,6-tetrahydi pyrazino[ 1 ,2-a]quinoxaline- 1 ,4(4aH)-dione;

or a pharmaceutically acceptable salt thereof,

A compound of claim 1, comprising a compound of formula (II)

or a pharmaceutically acceptable salt thereof, wherein

X^b, Y^b, Q^b, and Z^b are each CR^a, or one or two of X^b, Y^b, Q^b, and Z^b is N and the others are CR^¾; p is 0, 1, 2, or 3;

a

R is hydrogen, fluorine, chlorine, -Ci-4 alkyl, -S(Ci-6 alkyl), or hydroxy;

R^lb is selected from hydrogen, aryl, heteroaryl, and -Ci -6 alkyl, wherein said aryl, heteroaryl, and alkyl, moiety is substituted with 0, 1, 2, or 3 groups selected from halogen, hydroxy,

-O-Ci-6 alkyl, -Ci-6 alkyl, and -S(Ci-6 alkyl); and each R^2b is independently selected from halogen, hydroxy, -O-Ci -3 alkyl, -Ci-3 alkyl, and -S(Ci -3 alkyl), wherein said alkyl moiety is substituted with 0, 1, 2, or 3 groups selected from halogen, hydroxy, -S(Ci-3 alkyl), and-O-Ci-3 alkyl.

15. A compound of claim 14, or a pharmaceutically acceptable salt thereof, wherein X , Y^b, Q^b, and Z^b are each CH; and R^lb is selected from phenyl, heteroaryl, and -Ci-3 alkyl, wherein said phenyl, heteroaryl, and alkyl, moiety is substituted with 0, 1, 2, or 3 groups selected from halogen, hydroxy, -O-Ci-6 alkyl, -Ci-6 alkyl, and -S(Ci-6 alkyl).

16. A pharmaceutical composition comprising a therapeutically effective amount of a compound of claim 1, or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable carrier. 17. Use of a pharmaceutical composition of claim 1 for the treatment of a disease or disorder mediated by the muscarinic Ml receptor, wherein said disease or disorder is selected from the group consisting of Alzheimer's disease, schizophrenia, pain and sleep disorders.

18. Use of a compound of claim 1 or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable carrier, for the manufacture of a medicament for the treatment of a disease or disorder mediated by the muscarinic Ml receptor, wherein said disease or disorder is selected from the group consisting of Alzheimer's disease, schizophrenia, pain and sleep disorders. 19. A method of treating a disease or disorder mediated by the muscarinic Ml receptor, wherein said disease or disorder is selected from the group consisting of Alzheimer's disease, schizophrenia, pain and sleep disorders in a patient in need thereof, comprising administering to the patient a therapeutically effective amount of a compound of claim 1 or a pharmaceutically acceptable salt thereof, and a pharmaceutically acceptable carrier.