HK1176351A - Method for preparation of carbamic acid (r)-1-aryl-2-tetrazolyl-ethyl ester - Google Patents

Abstract

Disclosed is a method for the preparation of carbamic acid (R)-1-aryl-2-tetrazolyl-ethyl ester, comprising the asymmetric reduction of arylketone and the carbamation of alcohol.

Description

Process for the preparation of carbamic acid (R) -1-aryl-2-tetrazolyl-ethyl ester

Technical Field

The invention relates to a method for preparing carbamic acid (R) -1-aryl-2-tetrazolyl-ethyl ester. More specifically, the present invention relates to a process for the preparation of (R) -1-aryl-2-tetrazolyl-ethyl carbamate, comprising asymmetric reduction of aryl ketones.

Background

(R) -1-aryl-2-tetrazolyl-ethyl carbamates (R) -2-tetrazolyl-ethyl esters having anti-spasmodic activity (hereinafter "carbamate compounds") are useful in the treatment of central nervous system disorders including, inter alia, anxiety, depression, spasticity, epilepsy, migraine, manic depression, drug abuse, smoking, Attention Deficit Hyperactivity Disorder (ADHD), obesity, insomnia, neuropathic pain, stroke, cognitive disorders, neurodegeneration, stroke, and muscle spasms, as disclosed in U.S. patent application publication No.2006/0258718A 1.

Carbamate compounds are classified into two positional isomers according to the position of the "N" in their tetrazole moiety: tetrazol-1-yl (hereinafter referred to as "1N tetrazole") and tetrazol-2-yl (hereinafter referred to as "2N tetrazole"). The introduction of tetrazole in the preparation of the carbamate compound results in a 1: 1 mixture of the two positional isomers, which need to be separated separately for pharmaceutical use.

Due to the chirality, carbamate compounds must have high optical purity as well as high chemical purity when used as pharmaceuticals.

In this regard, U.S. patent application publication No.2006/0258718a1 uses a pure enantiomer (R) -aryl-oxetane ((R) -aryl-oxirane) as a starting material, which is converted to an alcohol intermediate by a ring-opening reaction with tetrazole in a solvent in the presence of a suitable base, followed by introduction of a carbamoyl group to the alcohol intermediate. For the isolation and purification of the 1N and 2N positional isomers thus prepared, column chromatography may be performed after the formation of the alcohol intermediate or carbamate.

Disclosure of Invention

Technical problem

For use in the above preparation processes, (R) -2-aryl-oxetanes can be synthesized from optically active starting materials such as substituted (R) -mandelic acid derivatives by various routes, or obtained by asymmetric reduction-cyclization of α -haloaryl ketones, or by separation of racemic 2-aryl-oxetane mixtures into their individual enantiomers. As such, (R) -2-aryl-oxetane is an expensive compound.

In addition, the ring-opening reaction of (R) -2-aryl-oxetane with tetrazole needs to be carried out at a relatively high temperature due to the low nucleophilicity of tetrazole. However, the ring-opening reaction still has a high risk of runaway reaction due to the spontaneous decomposition of tetrazole starting at 110-120 ℃.

In terms of selectivity of the reaction, since (R) -2-aryl-oxetane and tetrazole each have two reactive sites, the ring-opening reaction between them gives a 1N-or 2N-tetrazole substituent at the benzyl or terminal position, resulting in a mixture of a total of 4 positional isomers. For this reason, the individual positional isomers are low in yield and difficult to isolate and purify.

Technical scheme

Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a novel method for preparing novel (R) -1-aryl-2-tetrazolyl-ethyl esters.

In order to accomplish the above object, the present invention provides a method for preparing carbamic acid (R) -1-aryl-2-tetrazolyl-ethyl ester represented by chemical formula 1, comprising: subjecting the aryl ketone represented by chemical formula 2 to (R) -selective asymmetric reduction to form an (R) -configured alcohol compound represented by chemical formula 5; and carbamylating the alcohol:

chemical formula 1

[ chemical formula 1]

Chemical formula 2

[ chemical formula 2]

Chemical formula 5

[ chemical formula 5]

Wherein the content of the first and second substances,

R₁and R₂Independently selected from the group consisting of: hydrogen, halogen, perfluoroalkyl, alkyl of 1 to 8 carbon atoms, thioalkoxy of 1 to 8 carbon atoms, and alkoxy of 1 to 8 carbon atoms; and

A₁and A₂One of which is CH and the other is N.

Advantageous effects of the invention

The synthesis of aryl ketones of chemical formula 2 from the compounds of chemical formulae 8 and 9 is economically advantageous because they are commercially available, inexpensive compounds. In addition, the substitution reaction can be performed under relatively mild conditions, as compared to the ring-opening reaction of (R) -2-aryl-oxetane and tetrazole. The process according to the invention thus ensures process safety despite the use of potentially explosive tetrazoles and ensures high product yields and a simple purification method without the production of unwanted positional isomers at the benzyl position.

Best mode for carrying out the invention

According to one embodiment of the present invention, there is provided a method comprising (R) -selective asymmetric reduction of aryl ketone represented by the following chemical formula 2 and carbamation of alcohol compound represented by the following chemical formula 5 to prepare carbamic acid (R) -1-aryl-2-tetrazolyl-ethyl ester represented by the following chemical formula 1.

[ chemical formula 1]

[ chemical formula 2]

[ chemical formula 5]

Wherein the content of the first and second substances,

R₁and R₂Independently selected from the group consisting of: hydrogen, halogen, perfluoroalkyl, alkyl of 1 to 8 carbon atoms, thioalkoxy of 1 to 8 carbon atoms, and alkoxy of 1 to 8 carbon atoms; and

A₁and A₂One of which is CH and the other is N.

Modes for carrying out the invention

The aryl ketone of chemical formula 2, which is used as a starting material for the preparation method of the present invention, can be synthesized, for example, by a substitution reaction between the aryl ketone of chemical formula 8 and the tetrazole of chemical formula 9:

chemical formula 8

[ chemical formula 8]

Chemical formula 9

[ chemical formula 9]

Wherein the content of the first and second substances,

R₁and R₂Is as defined above; and

x is a leaving group such as halide or sulfonate.

The synthesis of aryl ketones of chemical formula 2 from the compounds of chemical formulae 8 and 9 is economically advantageous because they are commercially available, inexpensive compounds. In addition, the substitution reaction can be performed under relatively mild conditions, as compared to the ring-opening reaction of (R) -2-aryl-oxetane and tetrazole. The process according to the invention thus ensures process safety despite the use of potentially explosive tetrazoles and ensures high product yields and a simple purification method without the production of unwanted positional isomers at the benzyl position of the product.

The aryl ketone of chemical formula 2, which can be synthesized by a substitution reaction with tetrazole, can be isolated and purified by commercially available crystallization in a mixture of positional isomers including 1N aryl ketone of chemical formula 3 below and 2N aryl ketone of chemical formula 4 below.

Chemical formula 3

[ chemical formula 3]

Chemical formula 4

[ chemical formula 4]

The crystals employed in the present invention may include: to the substitution reaction product, i.e., the mixture of positional isomers, is added a solubilizing agent, followed by the addition of a precipitating agent. Optionally, the crystallization may further include: after precipitation the precipitate was filtered, the filtrate was concentrated and additional precipitant was added.

Examples of solubilizers that are used for illustration and not limitation include acetone, acetonitrile, tetrahydrofuran, ethyl acetate, dichloromethane, chloroform, 1, 4-dioxane, and lower alcohols of 1 to 4 carbon atoms, and combinations thereof. The solubilizer may be used in an amount of 0 to 20ml (v/w) depending on the weight (g) of the mixture of regioisomers. When the solubilizer is used in an amount of zero (0) ml (v/w), it means that the filtrate is not diluted and the subsequent additives are added immediately.

Examples of the precipitant include, but are not limited to, water, C1-C4 lower alcohols, diethyl ether, pentane, hexane, cyclohexane, heptane, and combinations thereof. The precipitant may be slowly added in an amount of 0-40ml (v/w) according to the weight (g) of the mixture of positional isomers. When the amount of the precipitant added is zero (0) ml, it means that the precipitant is not added, and left to stand or cooled to cause precipitation.

The precipitate obtained by adding the precipitant is filtered to produce the 1N aryl ketone of chemical formula 3 as a high-purity crystal.

On the other hand, the filtrate obtained after the filtration step may be concentrated to increase the ratio of the precipitant and the solubilizer, thereby obtaining the 2N aryl ketone of chemical formula 4 with high purity. One of ordinary skill in the art can determine the appropriate filtrate concentration ratio. For example, concentration is carried out until the solvent is completely removed, and then the solubilizer and precipitant are added as described above.

Unlike column chromatography, the crystals do not present many difficulties in industrial application.

The (R) -selective asymmetric reduction converts the aryl ketone of chemical formula 2 into an alcohol compound having (R) -configuration shown in the following chemical formula 5.

[ chemical formula 2]

[ chemical formula 5]

Wherein the content of the first and second substances,

R₁and R₂Independently selected from the group consisting of: hydrogen, halogen, perfluoroalkyl, alkyl of 1 to 8 carbon atoms, thioalkoxy of 1 to 8 carbon atoms, and alkoxy of 1 to 8 carbon atoms; and

A₁and A₂One of which is CH and the other is N.

The (R) -selective asymmetric reduction can be achieved, for example, biologically or chemically.

According to one embodiment of the present invention, in the method for preparing (R) -1-aryl-2-tetrazolyl-ethyl carbamate, the aryl ketone compound of chemical formula 2 is converted into an alcohol compound having (R) -configuration with optical high purity through bio-asymmetric reduction.

The bioasymmetric reduction can be achieved at an appropriate temperature in a buffer containing a microorganism strain capable of producing an oxidoreductase, an arylketone compound of chemical formula 2, and a co-substrate (cosubstrate). Examples of microbial strains capable of producing oxidoreductases include: yeasts of the genus Candida, such as Candida parapsilosis (Candida parapsilosis) or Candida rugosa (Candida rugosa); a yeast of the genus Pichia, such as Pichia anomala (Pichia anomala) or Pichia jadei (Pichia jadinii); yeasts of the Saccharomyces genus, such as Saccharomyces cerevisiae (Baker's yeast), Saccharomyces cerevisiae (Saccharomyces cerevisiae) or Saccharomyces pastorianus (Saccharomyces pastorianus); other yeasts such as Rhodotorula mucilaginosa (Rhodotorula mucor) or Trigonopsis variabilis (Trigonopsis variabilis); bacteria, such as Klebsiella pneumoniae (Klebsiella pneumoniae), Enterobacter cloacae (Enterobacter cloacae), Erwinia herbicola (Erwinia herbicoloa), Micrococcus luteus (Micrococcus luteus), Bacillus stearothermophilus (Bacillus stearothermophilus), Rhodococcus erythropolis (Rhodococcus erythropolis) or Rhodococcus rhodochrous (Rhodococcus rhodochrous); fungi, such as Mucor racemosus (Mucor racemosus) or Geotrichum candidum (Geotrichum candidum), etc.

The microbial strain capable of producing an oxidoreductase may be used in an amount of about 0.1-10g per gram of the aryl ketone of chemical formula 2.

To increase the rate of the biological asymmetric reduction, additional coenzymes such as Nicotinamide Adenine Dinucleotide Phosphate (NADP) or Nicotinamide Adenine Dinucleotide (NAD) may also be added to the buffer in an amount of about 0.1-1mg per gram of the aryl ketone of formula 2.

The coenzyme, NADP or NAD, respectively, can be converted into its reduced form, NADPH or NADH, by means of an oxidoreductase and/or a cosubstrate, respectively.

Examples of co-substrates include: sugars such as glucose, glycerol or sucrose; and alcohols such as methanol, ethanol, 1-propanol, isopropanol, 1-butanol, 2-pentanol, 2-methylpentanol, 2-hexanol, 2-heptanol, 2-octanol, cyclopentanol, cyclohexanol, 2-methyl-2-butanol, etc. Among the aforementioned alcohols, methanol, 1-propanol, 1-butanol and 2-methyl-2-butanol are preferable.

The buffer used in the biological asymmetric reduction may be PBS (phosphate buffered saline) or an aqueous solution of sodium phosphate, potassium phosphate or triethanolamine, for example, at a pH of 6 to 8.

The biological asymmetric reduction can be carried out at 10-45 ℃.

In addition to being economical and environmentally friendly, bioselective reductions have very high enantioselectivities. Therefore, (R) -configured alcohol compounds of high optical purity can be obtained under the above reaction conditions in the presence of an enzyme.

In another embodiment of the present invention, in the process for preparing (R) -1-aryl-2-tetrazolyl-ethyl carbamate, the aryl ketone compound of chemical formula 2 is converted into an alcohol compound having (R) -configuration with optical high purity under asymmetric conditions.

Chemical asymmetric reduction can be achieved, for example, by reaction with a chiral borane reducing agent in an organic solvent at an appropriate temperature, or by asymmetric catalytic hydrogenation or asymmetric catalytic transfer hydrogenation.

In connection with mining1-4 equivalent of (-) -B-diisopinocampheylchloroborane sodium (abbreviated as "(-) -DIP-Cl") or (R) -2-methyl-CBS-oxazaborolidine/borane (abbreviated as "(R) -CBS/BH) is added by using chiral borane reducing agent₃") is added to a solution of the arylketone compound of chemical formula 2 in an organic solvent such as diethyl ether, tetrahydrofuran, 1, 4-dioxane, acetonitrile, dichloromethane, chloroform or a mixture thereof, and then reacted at about-10 ℃ to about 60 ℃.

Asymmetric catalytic hydrogenation can be carried out as follows: 0.0004 to 0.2 equivalent of an inorganic base is added to a solution of 0.0002 to 0.1 equivalent of (R) -diphosphino-ruthenium (II) - (R, R) -chiral diamine complex catalyst in an organic solvent such as isopropanol, methanol, ethanol or tert-butanol. The aryl ketone compound of chemical formula 2 is added and the resulting solution is maintained at about-10 ℃ to about 60 ℃ under a hydrogen pressure of 1 to 20 atm. A non-limiting example for the asymmetric catalytic hydrogenation is dichloro [ (R) - (+) -2, 2 '-bis (diphenylphosphino) 1, 1' -binaphthyl ] [ (1R, 2R) - (+) -1, 2-diphenylethylenediamine ] ruthenium (II) shown in the following chemical formula 10.

Chemical formula 10

[ chemical formula 10]

While asymmetric catalytic transfer hydrogenation can be carried out by adding 0.001-0.1 equivalent of an [ S, S ] -monosulfonate diamine-M (II) aromatic hydrocarbon complex catalyst, wherein M is ruthenium or rhodium, to a solution of the aryl ketone compound of formula 2 in 5: 2 formic acid-triethylamine azeotrope or isopropanol at about-10 deg.C to 60 deg.C. A non-limiting example of the catalyst for asymmetric catalytic transfer hydrogenation may be chloro { [ (1S, 2S) - (+) -amino-1, 2-diphenylethyl ] (4-toluenesulfonyl) amino } (p-isopropyltoluene) ruthenium (II) shown in the following chemical formula 11.

Chemical formula 11

[ chemical formula 11]

The alcohol compound obtained by asymmetric reduction may exist as a mixture of positional isomers of 1N alcohol of chemical formula 6 and 2N alcohol of chemical formula 7, which can be separated and purified into individual positional isomers with high purity by crystallization:

chemical formula 6

[ chemical formula 6]

Chemical formula 7

[ chemical formula 7]

Crystallization may include adding a solubilizing agent to the mixture of regioisomers resulting from the asymmetric reduction; adding a precipitating agent, and optionally filtering the precipitate; and concentrating the filtrate and adding additional precipitant.

Examples of the solubilizer for crystallization include acetone, acetonitrile, tetrahydrofuran, ethyl acetate, dichloromethane, chloroform, 1, 4-dioxane and lower alcohols of 1 to 4 carbon atoms and mixtures thereof, but are not limited thereto. The solubilizer may be used in an amount of 0 to 20ml (v/w) based on the weight (g) of the mixture of regioisomers.

Non-limiting examples of the precipitant include water, lower alcohols of 1 to 4 carbon atoms, diethyl ether, pentane, hexane, cyclohexane, heptane, and mixtures thereof, but are not limited thereto. The precipitant may be slowly added in an amount of 0-40ml (v/w) according to the weight (g) of the mixture of positional isomers.

After addition of the precipitant, the 1N alcohol (6) can be obtained in high purity in the form of a precipitate by filtration.

Furthermore, 2N alcohol (7) of very high purity can be obtained in the form of crystals by concentrating the filtrate and increasing the ratio of precipitant and solubilizer.

When the positional isomers of the aryl ketones of chemical formula 2 have been separated and purified, these crystallization steps may be omitted.

Introduction of a carbamoyl moiety into the (R) -configured alcohol compound of chemical formula 5 yields a carbamate having (R) -configuration shown in chemical formula 1.

[ chemical formula 5]

[ chemical formula 1]

Wherein the content of the first and second substances,

R₁and R₂Independently selected from the group consisting of: hydrogen, halogen, perfluoroalkyl, alkyl of 1 to 8 carbon atoms, thioalkoxy of 1 to 8 carbon atoms, and alkoxy of 1 to 8 carbon atoms; and

A₁and A₂One of which is CH and the other is N.

In the carbamylation step, for example, inorganic cyanate-organic acid, isocyanate-water, or carbonyl compound-aqueous ammonia may be used to introduce the carbamoyl moiety.

In the carbamylation with inorganic cyanate-organic acid, (R) -configured alcohol compound of chemical formula 5 is dissolved in an organic solvent, for example, diethyl ether, tetrahydrofuran, 1, 4-dioxane, acetonitrile, dichloromethane, chloroform or a mixture thereof, and mixed with 1-4 equivalents of inorganic cyanate such as sodium cyanate and organic acid such as methanesulfonic acid or acetic acid, and then reacted at about-10 to 70 ℃.

With respect to the use of isocyanate-water, 1-4 equivalents of isocyanic acid such as chlorosulfonic isocyanate, trichloroacetyl isocyanate, trimethylsilyl isocyanate are added to a solution of (R) -configured alcohol compound of chemical formula 5 and an organic solvent such as diethyl ether, tetrahydrofuran, 1, 4-dioxane, acetonitrile, dichloromethane, chloroform or a mixture thereof, and reacted at about-50 to 40 ℃. Then, without purification, 1 to 20 equivalents of water are added for hydrolysis.

Regarding the use of the carbonyl compound-aqueous ammonia, 1 to 4 equivalents of the carbonyl compound, for example, 1, 1' -carbonylimidazole, carbamoyl chloride, disuccinylcarbonate, phosgene, triphosgene, or chloroformate, are added to a solution of the (R) -configured alcohol compound of chemical formula 5 in an organic solvent such as diethyl ether, tetrahydrofuran, 1, 4-dioxane, acetonitrile, dichloromethane, chloroform, or a mixture thereof, and reacted at about-10 to 70 ℃, followed by the addition of 1 to 4 equivalents of aqueous ammonia, without purification.

After carbamylation, the resulting carbamate compound of chemical formula 1 can be purified to higher optical and chemical purity by subsequent crystallization. The crystallization comprises adding a solubilizer to the carbamylation product; the precipitant is then added, and optionally the precipitate is filtered, and additional precipitant is added. For pharmaceutical use, the final purification is preferably always carried out before the carbamoylation product is used, but a crystallization step may also be carried out in the early stages of the process.

Non-limiting examples of the solubilizer include acetone, acetonitrile, tetrahydrofuran, ethyl acetate, dichloromethane, chloroform, 1, 4-dioxane and lower alcohols of 1 to 4 carbon atoms and mixtures thereof. The solubilizer may be used in an amount of 0 to 20ml (v/w) depending on the weight (g) of the reaction product.

Non-limiting examples of precipitants include water, lower alcohols of 1-4 carbon atoms, diethyl ether, pentane, hexane, cyclohexane, heptane, and mixtures thereof. The precipitant may be slowly added in an amount of 0 to 40ml (v/w) according to the weight (g) of the reaction product. Including biological or chemical asymmetric reduction, the method of the present invention can provide an optically highly pure carbamate compound. In addition, the mild reaction conditions required by the invention ensure the safety of the process. Furthermore, crystallization steps suitable for large-scale production before or after asymmetric reduction or after carbamylation can give carbamate compounds of higher chemical purity.

As shown in the following examples, carbamate compounds prepared according to the present invention are useful in the treatment of Central Nervous System (CNS) disorders such as spasticity.

The present invention will be better understood from the following examples which are set forth for the purpose of illustration and are not to be construed as limiting the present invention.

Examples

Preparation of tetrazolylarylketones

Preparation example 1: preparation of 1- (2-chlorophenyl) -2- (1, 2, 3, 4-tetrazol-1-yl) ethan-1-one

To a suspension of 2-bromo-2' -chloroacetophenone (228.3g, 0.978mol) and potassium carbonate (161.6g, 1.170mol) in acetonitrile (2000mL) was added 35 w/w% 1H-tetrazole dimethylformamide (215.1g, 1.080mol) at room temperature. The reaction was stirred at 45 ℃ for 2h and about 1500mL of solvent was distilled off under reduced pressure. The concentrate was diluted with ethyl acetate (2000mL) and washed with 10% brine (3X 2000 mL). The separated organic layer was distilled under reduced pressure to give 216.4g of an oily solid residue. To the solid residue in ethyl acetate (432mL) was added heptane (600mL) slowly. The precipitate formed was filtered at room temperature and washed to give 90.1g (0.405mol) of 1- (2-chlorophenyl) -2- (1, 2, 3, 4-tetrazol-1-yl) ethan-1-one (hereinafter referred to simply as "1N ketone").

¹H-NMR(CDCl₃)d8.87(s，1H)，d7.77(d，1H)，d7.39-7.62(m，3H)，d5.98(s，2H)

Preparation example 2: preparation of 1- (2-chlorophenyl) -2- (1, 2, 3, 4-tetrazol-2-yl) ethan-1-one

After the filtration step of preparative example 1, the filtrate was concentrated and dissolved in isopropanol (100mL), and heptane (400mL) was then added thereto to complete crystallization. Filtration and washing at 5 ℃ gave 94.7g (0.425mol) of 1- (2-chlorophenyl) -2- (1, 2, 3, 4-tetrazol-2-yl) ethan-1-one (hereinafter referred to as "2N-one") as a solid.

¹H-NMR(CDCl₃)d8.62(s，1H)，d7.72(d，1H)，d7.35-7.55(m，3H)，d6.17(s，2H)

Preparation of (R) -configured alcohol compounds by biological asymmetric reduction

Suitable for the biological asymmetric reduction are strains which express oxidoreductases. Such as baker's yeast (Jenico), commercially available strains in lyophilized form may be suitably considered for this reaction. Similar to other microbial strains, the strains stored in a deep freezer (Revco) were applied to LB plate medium (bacto tryptone: 1%, yeast extract: 0.5%, NaCl: 0.5%, glucose: 0.1%, agar: 1.5%) to form colonies. One of them was then inoculated into 3mL of LB medium placed in a tube and preincubated at 30 ℃ for 1 day. After completion of the pre-incubation, it was amplified to 300mL of LB medium in a 1L Erlenmeyerflash flask and incubated at 30 ℃ for 2 days. The pellet was centrifuged to form a pellet of the amount required for the reaction.

Preparation example 3: preparation of 1N alcohol Using Rhodotorula mucilaginosa

1- (2-chlorophenyl) -2- (1, 2, 3, 4-tetrazol-1-yl) ethan-1-one (100mg, 0.449mmol) prepared in preparation example 1 and nicotinamide adenine dinucleotide (NAD, 0.5mg) were cultured in the presence of Rhodotorula mucilaginosa KCTC7117(500mg) which is a microorganism strain producing oxidoreductase at room temperature for 4 days in PBS (10mL, pH7.0) containing 5% (w/v) glycerol, and after extraction with ethyl acetate (1mL), R-configurational alcohol, that is, (R) -1- (2-chlorophenyl) -2- (1, 2, 3, 4-tetrazol-1-yl) ethan-1-ol (hereinafter referred to as "1N alcohol") was obtained. The conversion and optical purity of the product are shown in table 1 below. The conversion (%), purity (%) and optical purity of the product were measured by HPLC and calculated by the following equations.

Conversion (%) ═ product area)/(reactant area + product area) x 100

Purity (%) - [ (product area)/(HPLC all peak area) ] × 100

Optical purity (%) - (area of R-configuration-area of S-configuration)/(area of R-configuration + area of S-configuration) ] × 100

¹H-NMR(CDCl₃)d8.74(s，1H)，d7.21-7.63(m，4H)，d5.57(m，1H)，d4.90(d，1H)，d4.50(d，1H)，d3.18(d，1H)

Preparation example 4: preparation of 2N alcohol Using Rhodotorula mucilaginosa

The same procedures as those conducted in production example 3 were repeated except for using 1- (2-chlorophenyl) -2- (1, 2, 3, 4-tetrazol-2-yl) ethan-1-one produced in production example 2 in place of 1- (2-chlorophenyl) -2- (1, 2, 3, 4-tetrazol-1-yl) ethan-1-one to obtain (R) -1- (2-chlorophenyl) -2- (1, 2, 3, 4-tetrazol-2-yl) ethan-1-ol (hereinafter referred to simply as "2N alcohol"). The conversion and optical purity of the product are shown in table 1 below.

¹H-NMR(CDCl₃)d8.55(s，1H)，d7.28-7.66(m，4H)，d5.73(d，1H)，d4.98(d，1H)，d4.83(d，1H)，d3.38(br，1H)

Preparation example 5: preparation of 1N alcohols Using Trigonopsis variabilis

The same procedure as in preparation example 3 was repeated except that Trigonopsis variabilis KCTC7263 was used instead of Rhodotorula mucilaginosa KCTC7117 as an oxidoreductase-producing microorganism strain to obtain 1N alcohol of R-configuration. The conversion and optical purity are shown in Table 1 below.

Preparation example 6: preparation of 2N alcohols Using Trigonopsis variabilis

The same procedure as in preparation example 4 was repeated except that Trigonopsis variabilis KCTC7263 was used instead of Rhodotorula mucilaginosa KCTC7117 as an oxidoreductase-producing microorganism strain to obtain 2N alcohol of R-configuration. The conversion and optical purity are shown in Table 1 below.

TABLE 1

[ Table 1]

Preparation examples 7 and 8: 1N alcohol production Using Candida Yeast

The same procedure as in preparation example 3 was repeated except that Candida parapsilosis (Candida parapsilosis) ATCC20179 or Candida rugosa (Candida rugosa) KCTC7292 was used in place of Rhodotorula mucilaginosa KCTC7117 as the oxidoreductase-producing microorganism strain, to obtain 1N alcohol in R-configuration. The conversion and optical purity are shown in Table 2 below.

Preparative examples 9 and 10: preparation of 2N alcohols Using Candida Yeast

The same procedure as in preparation example 4 was repeated except that Candida parapsilosis (Candida parapsilosis) ATCC20179 or Candida rugosa (Candida rugosa) KCTC7292 was used in place of Rhodotorula mucilaginosa KCTC7117 as the oxidoreductase-producing microorganism strain, to obtain 2N alcohol of R-configuration. The conversion and optical purity are shown in Table 2 below.

TABLE 2

[ Table 2]

Preparation examples 11 and 12: preparation of 1N alcohol by Pichia yeast

The same procedure as in preparation example 3 was repeated except that Pichia anomala (Pichia anomala) KCTC1206 or Pichia jadei (Pichia jadinii) KCTC7008 was used instead of Rhodotorula mucilaginosa KCTC7117 as an oxidoreductase-producing microorganism strain to obtain 1N alcohol of R-configuration. The conversion and optical purity are shown in Table 3 below.

Preparative examples 13 and 14: preparation of 2N alcohols Using Pichia Yeast

The same procedure as in preparation example 4 was repeated except that Pichia anomala (Pichia anomala) KCTC1206 or Pichia jadei (Pichia jadinii) KCTC7008 was used as the oxidoreductase-producing microorganism strain in place of Rhodotorula mucilaginosa KCTC7117 to obtain 2N alcohol of R-configuration. The conversion and optical purity are shown in Table 3 below.

TABLE 3

[ Table 3]

Preparation examples 15 to 20: 1N alcohol production Using Saccharomyces Yeast

The same procedure as in preparation example 4 was repeated except that Saccharomyces cerevisiae KCTC7108, Saccharomyces cerevisiae KCTC1205, Saccharomyces cerevisiae KCTC7107, Saccharomyces cerevisiae KCTC1552 or Saccharomyces pastorianus KCTC1218 was used as the oxidoreductase-producing microorganism strain in place of the Rhodotorula mucilaginosa KCTC7117 to obtain 1N alcohol in R-configuration. The conversion and optical purity are shown in Table 4 below.

Preparation examples 21 to 26: preparation of 2N alcohols Using Saccharomyces Yeast

The same procedure as in preparation example 4 was repeated except that Saccharomyces cerevisiae KCTC7108, Saccharomyces cerevisiae KCTC1205, Saccharomyces cerevisiae KCTC7107, Saccharomyces cerevisiae KCTC1552 or Saccharomyces pastorianus KCTC1218 was used as the oxidoreductase-producing microorganism strain in place of the Rhodotorula mucilaginosa KCTC7117 to obtain 2N alcohol in R-configuration. The conversion and optical purity are shown in Table 4 below.

TABLE 4

[ Table 4]

Preparation examples 27 to 30: preparation of 1N alcohols using bacteria

The same procedure as in preparation example 3 was repeated except that Klebsiella pneumoniae (Klebsiella pneumoniae) IFO3319, Bacillus stearothermophilus (Bacillus stearothermophilus) KCTC1752, Rhodococcus erythropolis (Rhodococcus erythropolis) KCCM40452 or Rhodococcus rhodochrous (Rhodococcus rhodochrous) ATCC21197 was used in place of Rhodotorula mucilaginosa KCTC7117 as a microorganism strain producing oxidoreductase, to obtain 1N alcohol in R-configuration. The conversion and optical purity are shown in Table 5 below.

Preparation examples 31 to 37: preparation of 2N alcohols using bacteria

The same procedure as in preparation example 4 was repeated except that Klebsiella pneumoniae (Klebsiella pneumoniae) IFO3319, Enterobacter cloacae (Enterobacter cloacae) KCTC2361, Erwinia herbicola (Erwinia herbicoloa) KCTC2104, Micrococcus luteus (Micrococcus luteus) KCTC1071, Bacillus stearothermophilus (Bacillus stearothermophilus) KCTC1752, Rhodococcus erythropolis (Rhodococcus erythropolis) KCCM40452 or Rhodococcus rhodochrous (Rhodococcus rhodochrous) ATCC21197 was used as the microorganism strain for producing oxidoreductase in place of Rhodotorula mucilaginosus KCTC7117 to obtain 2N alcohol of R-configuration. The conversion and optical purity are shown in Table 5 below.

TABLE 5

[ Table 5]

Preparative examples 38 and 39: preparation of 1N alcohols using fungi

The same procedure as in preparation example 3 was repeated except that Mucor racemosus (KCTC 6119), Geotrichum candidum (KCTC 6195), Geotrichum candidum (IFO 5767) or Geotrichum candidum (IFO 4597) was used as the oxidoreductase-producing microorganism strain in place of the Rhodotorula mucilaginosa KCTC7117, to obtain 1N alcohol of R-configuration. The conversion and optical purity are shown in Table 6 below.

Preparation examples 40 to 42: preparation of 2N alcohols using fungi

The same procedure as in preparation example 4 was repeated except that Mucor racemosus (KCTC 6119), Geotrichum candidum (KCTC 6195), Geotrichum candidum (IFO 5767) or Geotrichum candidum (IFO 4597) was used as the oxidoreductase-producing microorganism strain in place of the Rhodotorula mucilaginosa KCTC7117, to obtain 2N alcohol of R-configuration. The conversion and optical purity are shown in Table 6 below.

TABLE 6

[ Table 6]

Preparation of (R) -configured alcohol compounds by chemical asymmetric reduction

Preparation examples 43 and 44: preparation of 1N alcohols using chiral borane reducing agents

To a solution of the 1N ketone prepared in preparative example 1 (100mg, 0.449mmol) in tetrahydrofuran (1mL) at 0 ℃ was added 2 equivalents of a chiral borane reducing agent such as (-) -B-diisopinocampheylchloroborane or (R) -2-methyl-CBS-oxazalborane/borane. After stirring at room temperature for 24 hours, the mixture was extracted with ethyl acetate (1mL), and the results obtained were as shown in Table 7 below.

Preparation examples 45 and 46: preparation of 2N alcohols using chiral borane reducing agents

To a solution of the 2N ketone prepared in preparative example 2 (100mg, 0.449mmol) in tetrahydrofuran (1mL) at 0 ℃ was added 2 equivalents of a chiral borane reducing agent such as (-) -B-diisopinocampheylchloroborane or (R) -2-methyl-CBS-oxazalborane/borane. After stirring at room temperature for 24 hours, the mixture was extracted with ethyl acetate (1mL), and the results obtained were as shown in Table 7 below.

TABLE 7

[ Table 7]

Preparation examples 47 and 48: preparation of 1N and 2N alcohols by asymmetric catalytic transfer hydrogenation

The 1N ketone prepared in preparative example 1 or the 2N ketone prepared in preparative example 2 (222mg, 1.0mmol) was dissolved in a 5: 2 formic acid-triethylamine azeotrope (1.4mL) under argon. After the solution was cooled to 0 ℃ under an argon atmosphere, chloro { [ (1S, 2S) - (+) -amino-1, 2-biphenylethyl ] (4-toluenesulfonyl) amino } (p-isopropyltoluene) ruthenium (II) (2mg, 0.003mmol) of chemical formula 11 was added thereto. After stirring at room temperature for 48 hours, the mixture was extracted with ethyl acetate (2mL), and the results obtained were as shown in Table 8 below.

TABLE 8

[ Table 8]

Preparation of carbamates

Preparation example 49: preparation of (R) -1- (2-chlorophenyl) -2- (tetrazol-1-yl) ethyl carbamate

To PBS (1000mL, pH7.0) containing 5% (w/v) glycerol were added baker's yeast (50g) and the 1N ketone prepared in preparation example 1 (10g, 44.9mmol), along with nicotinamide adenine dinucleotide (NAD, 1 mg). The resulting reaction suspension was stirred at 30 ℃ for 4 days, and mixed with ethyl acetate (500 mL). After separation, the organic layer formed was washed with 10% brine (3 × 500 mL). Magnesium sulfate was added to the organic layer, and the resulting suspension was filtered. The filtrate was distilled under reduced pressure to give 8.5g of a solid residue, which was then dissolved in ethyl acetate (10mL) at 45 ℃ and cooled to room temperature. Heptane (20mL) was added slowly to initiate crystallization. The precipitate formed was filtered and washed to give 7.32g (32.6mmol) of 1- (2-chlorophenyl) -2- (1, 2, 3, 4-tetrazol-1-yl) ethan-1-ol (optical purity 99.9%). The precipitate was dissolved in dichloromethane (73mL), to which was added methanesulfonic acid (5.5mL, 84.7mmol) at 10 ℃ followed by the slow addition of sodium cyanate (4.24g, 65.2 mmol). The reaction mixture was stirred at 10 ℃ for 12h and washed with 10% brine (3X 100 mL). The resulting organic layer was concentrated under reduced pressure, and the concentrate was dissolved in isopropanol (14 mL). The solution was heated to 45 ℃ and cooled to room temperature to initiate crystallization to completion. The resulting precipitate was filtered and washed to give 7.84g (29.3mmol) of (R) -1- (2-chlorophenyl) -2- (tetrazol-1-yl) ethyl carbamate (> 99.0% purity, > 99.0% optical purity).

¹H-NMR (acetone-d)₆)d9.14(s，1H)，d7.31-7.59(m，4H)，6.42(m，1H)，d6.0-6.75(Br，2H)，d4.90(d，1H)，d5.03(m，2H)

Preparation example 50: preparation of (R) -1- (2-chlorophenyl) -2- (tetrazol-2-yl) ethyl carbamate

The 2N ketone prepared in preparative example 2 (15.5g, 69.6mmol) was dissolved in a 5: 2 formic acid-triethylamine azeotrope (60mL) under argon. To the solution was added chloro { [ (1S, 2S) - (+) -amino-1, 2-biphenylethyl ] (4-toluenesulfonyl) amino } (p-isopropyltoluene) ruthenium (II) (140mg, 0.220mmol) of chemical formula 11, followed by stirring at room temperature for 48 h. The solution was diluted with ethyl acetate (200mL) and washed with 10% brine (3X 100 mL). The obtained organic layer was dried over magnesium sulfate and filtered, and the filtrate was distilled under reduced pressure to give 14.8g (65.9mmol) of 1- (2-chlorophenyl) -2- (1, 2, 3, 4-tetrazol-2-yl) ethan-1-ol as an oily residue (optical purity 87.8%). Tetrahydrofuran (150mL) was added thereto. After cooling to-15 ℃, chlorosulfonyl isocyanate (6.9mL, 79.2mmol) was added slowly and stirred at-10 ℃ for 2 h. Water (10mL) was added slowly to quench the reaction. The resulting solution was concentrated under reduced pressure until about 100mL of solvent was removed. The concentrate was diluted with ethyl acetate (200mL) and washed with 10% brine (3X 150 mL). The organic layer was concentrated under reduced pressure, the concentrate was dissolved in isopropanol (30mL), and heptane (90mL) was slowly added thereto to complete crystallization. The resulting precipitate was filtered and washed to give 15.4g (57.5mmol) of (R) -1- (2-chlorophenyl) -2- (tetrazol-2-yl) carbamic acid ethyl ester (purity > 99.0%, optical purity > 99.0%).

¹H-NMR (acetone-d)₆)d8.74(s，1H)，d7.38-7.54(m，4H)，d6.59(m，1H)，d6.16(Br，2H)，d4.90(d，1H)，d5.09(m，2H)

As described so far, urethane compounds having high optical and chemical purities can be economically prepared according to the present invention.

Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Claims (18)

1. A method for preparing aryl-2-tetrazolyl-ethyl carbamate represented by chemical formula 1, comprising:

subjecting the aryl ketone represented by chemical formula 2 to (R) -selective asymmetric reduction to form an (R) -configured alcohol compound represented by chemical formula 5; and

carbamylating the alcohol;

[ chemical formula 1]

[ chemical formula 2]

[ chemical formula 5]

Wherein the content of the first and second substances,

R₁and R₂Independently selected from the group consisting of: hydrogen, halogen, perfluoroalkyl, alkyl of 1 to 8 carbon atoms, thioalkoxy of 1 to 8 carbon atoms, and alkoxy of 1 to 8 carbon atoms; and

A₁and A₂One of which is CH and the other is N.

2. The method of claim 1, wherein the (R) -selective asymmetric reduction is achieved by biological asymmetric reduction or chemical asymmetric reduction.

3. The method of claim 2, wherein the bioasymmetric reduction is performed in a buffer containing the aryl ketone of formula 2, a microbial strain capable of producing an oxidoreductase, and a co-substrate.

4. The method according to claim 3, wherein the microbial strain is selected from the group consisting of: yeasts of the genus Candida, including Candida parapsilosis (Candida parapsilosis) and Candida rugosa (Candida rugosa); pichia yeasts including Pichia anomala (Pichia anomala) and Pichia jadei (Pichia jadinii); saccharomyces yeasts including Baker's yeast, Saccharomyces cerevisiae and Saccharomyces pastorianus; yeasts including Rhodotorula mucilaginosa (Rhodotorula mucilaginosa) and Trigonopsis variabilis (Trigonopsis variabilis); bacteria including Klebsiella pneumoniae (Klebsiella pneumoniae), Enterobacter cloacae (Enterobacter cloacae), Erwinia herbicola (Erwinia herbica), Micrococcus luteus (Micrococcus luteus), Bacillus stearothermophilus (Bacillus stearothermophilus), Rhodococcus erythropolis (Rhodococcus erythropolis), and Rhodococcus rhodochrous (Rhodococcus rhodochrous); fungi including Mucor racemosus (Mucor racemosus) and geotrichum candidum (geotrichum candidum); and combinations thereof.

5. The method of claim 2, wherein the chemically asymmetric reduction is achieved with a chiral borane reducing agent or by asymmetric catalytic hydrogenation or asymmetric catalytic transfer hydrogenation.

6. The method of claim 5, wherein the chiral borane reducing agent is (-) -B-diisopinocampheylchloroborane or (R) -2-methyl-CBS-oxazaborolidine/borane.

7. The method of claim 5, wherein the asymmetric catalytic hydrogenation is performed by reacting the aryl ketone of chemical formula 2 with hydrogen in the presence of (R) -diphosphino-ruthenium (II) - (R, R) -chiral diamine complex catalyst.

8. The process of claim 5, wherein the asymmetric catalytic transfer hydrogenation is carried out by reacting an aryl ketone of formula 2 with formic acid-triethylamine or isopropanol-inorganic base in the presence of [ S, S ] -monosulfonate diamine-M (II) arene complex catalyst system, wherein M represents ruthenium or rhodium.

9. The method of claim 1, wherein the carbamylation step is performed by reacting the (R) -configured alcohol compound of chemical formula 5 with an inorganic cyanate and an organic acid.

10. The method of claim 1, wherein the carbamylation step is performed by hydrolyzing a reaction product between an (R) -configured alcohol compound of chemical formula 5 and an isocyanate compound selected from the group consisting of: chlorosulfonic isocyanate, trichloroacetyl isocyanate and trimethylsilyl isocyanate.

11. The method of claim 1, wherein the carbamylation step is performed by introducing aqueous ammonia to a reaction product between an (R) -configured alcohol compound of chemical formula 5 and a carbonyl compound including 1, 1' -carbonylimidazole, carbamoyl halide, disuccinylcarbonate, phosgene, triphosgene, or chloroformate.

12. The process of claim 1, further comprising a crystallization step after at least one of the (R) -selective asymmetric reduction step and the carbamylation step.

13. The method of claim 12, wherein the crystallizing step comprises:

adding a solubilizing agent selected from the group consisting of acetone, acetonitrile, tetrahydrofuran, ethyl acetate, dichloromethane, chloroform, 1, 4-dioxane, lower alcohols having 1 to 4 carbon atoms and mixtures thereof to the reaction product; and

adding a precipitating agent selected from the group consisting of water, lower alcohols of 1 to 4 carbon atoms, diethyl ether, pentane, hexane, cyclohexane, heptane, and mixtures thereof.

14. The method of claim 1, further comprising the step of preparing the aryl ketone of chemical formula 2 by a substitution reaction between the aryl ketone of chemical formula 8 and the tetrazole of chemical formula 9:

[ chemical formula 8]

[ chemical formula 9]

Wherein the content of the first and second substances,

R₁and R₂As defined in claim 1; and

x is a leaving group selected from halide and sulfonate.

15. The method of claim 14, further comprising a crystallization step comprising:

adding a solubilizing agent selected from the group consisting of acetone, acetonitrile, tetrahydrofuran, ethyl acetate, dichloromethane, chloroform, 1, 4-dioxane, lower alcohols having 1 to 4 carbon atoms and mixtures thereof to the product obtained by the substitution reaction; and

adding a precipitating agent selected from the group consisting of water, lower alcohols of 1 to 4 carbon atoms, diethyl ether, pentane, hexane, cyclohexane, heptane, and mixtures thereof.

16. A method for preparing an alcohol compound represented by the following chemical formula 5 by (R) -selective asymmetric reduction of an aryl ketone represented by the following chemical formula 2, wherein the (R) -selective asymmetric reduction is achieved by biological asymmetric reduction or chemical asymmetric reduction:

[ chemical formula 2]

[ chemical formula 5]

Wherein the content of the first and second substances,

R₁and R₂Independently selected from the group consisting of: hydrogen, halogen, perfluoroalkyl, 1-8 carbon atomsAlkyl of 1 to 8 carbon atoms, thioalkoxy of 1 to 8 carbon atoms, and alkoxy of 1 to 8 carbon atoms; and

A₁and A₂One of which is CH and the other is N.

17. The method of claim 16, wherein the bioasymmetric reduction is performed in a buffer containing the aryl ketone of formula 2, a microbial strain capable of producing an oxidoreductase, and a co-substrate.

18. The method of claim 16, wherein the chemically asymmetric reduction is achieved with a chiral borane reducing agent or by asymmetric catalytic hydrogenation or asymmetric catalytic transfer hydrogenation.