KR100981555B1 - The Novel Preparation Method Of 2R,3S-3-substitutedmethyl-oxiran-2-yl methanol - Google Patents

Abstract

The present invention is an optical isomer comprising the step of hydrolyzing a racemate cis- (3- (substituted methyl) oxiran-2-yl) methyl acetate with a hydrolysis enzyme PPL (porcine pancreatic lipase) in a reaction solvent. Provided is a process for preparing (2R, 3S)-(3- (substitutedmethyl) -oxirane-2-yl) methanol in high purity and high yield.

Porcine pancreatic lipase (PPL), dynamic splitting, optical isomer

Description

Novel Preparation Method Of (2R, 3S)-(3- (substitutedmethyl) -oxiran-2 (2R, 3S)-(3- (substitutedmethyl) -oxirane-2-yl) methanol -yl) methanol}

The present invention relates to a process for the stereoselective preparation of (2R, 3S)-(3- (substitutedmethyl) -oxirane-2-yl) methanol.

3- (benzyloxymethyl) oxirane-2-carbaldehyde can be represented by the following structural formula 1, and all four carbons are fully functionalized compounds and are important structural units of biologically active natural products (Lanier. M .; Pastor, R. Tetrahedron Lett . 1995 , 36 , 2491-2492; (b) Righi, G .; Rumboldt, G. J. Org . Chem . 1996 , 61 , 3557-3560; (c) Concellon, JM; Bardales, E. Org . Lett . 2002 , 4 , 189-191; (d) Ichikawa, E .; Kato, K. Synthesis 2002 , 1-28; (e) Tosaki, S .; Nemoto, T .; Ohshima, T .; Shibasaki, M. Org. Lett . 2003 , 5 , 495-498; (f) Concellon, JM; Bardales, E .; Llavona, R. J. Org . Chem . 2003 , 68 , 1585-1588. (In Structural Formula 1 below, Bn means benzyl group).

[Formula 1]

In particular, the optically purely isomer of the compound of Formula 1 may be used in total synthesis through regioselective and stereoselective ring opening reaction, exchange reaction (metathesis) or asymmetric aldol condensation. Used as various intermediates. For example, the acetonide form of the cis-compound of Structural Formula 1 is used as a starting material in the total synthesis of cyclic guanidine-sugar, and the methyl group is located at the 3-carbon position of the cis-compound. Substituted compounds are used as critical intermediates that constitute the interior of the three rings of phomactin A (see Mohr, PJ; Halcomb, RL Org . Lett . 2002 , 4 , 2413-2416).

In addition, the compound of the formula Baylis-Hillman reaction (Krishna, PR; Lopinti, KR; Kannan, V. Tetrahedron Lett . 2004 , 45 , 7874-7850), Wittig reaction (Choudary, BM; Mahendar, K .; Kantam, ML; Ranganath, KVS;.... Athar, T Adv Synth Cactal 2006, see 348, 1977-1985), Mukai Yamato al dolrise Orientation [Mukaiyama aldolisation (Ruland, Y .; Noereuil, P. (See Baltas, M. Tetrahedron 2005 , 61 , 8895-8903).

Therefore, the development of efficient methods for obtaining the optical isomers of the above structural compounds, which are used as intermediates in the total synthesis of many useful materials, is currently a major issue. In addition, in the method for preparing the formula 1 compounds with certain optical isomer of (2 R, 3 S) -3- substituted oxirane-2-carbaldehyde of the, possible to use as starting material (-) - ( 2 R, 3 S) - oxiran-2-yl-is also required development of efficient stereoselective method of methanol.

Porcine pancreatic lipase (PPL) is a hydrolysis and transesterification enzyme, and has high purity and low production cost among lipases, and is known to be more lipophilic than other lipases. Crude PPL also increases their surface in water-organic solvents, and water, which is essentially present in the interior around the enzyme surface, maintains lipase activity and allows the substrate to bind better to the surface of the enzyme in organic solvents. (See Hazarika, S .; Goswami, P .; Dutta, NN; Hazarika, AK Chem . Eng . J. 2002 , 85 , 61-68.). However, very few examples of PPL have been used for kinetic resolution of oxirane compounds, which are molecules of low molecular weight. For example, the dynamic cleavage of cis-3-((benzyloxymethyl) oxan-2-yl) methanol via acetyl exchange reaction with PPL is cis-(+)-(2S, 3R) -oxirane-2 It is only reported that day-methanol occurs better (see Ferenc Faigl Angelika Thurner Melinda Battancs Ferenc Farkas Laszlo Poppe Viktoria Bodai Ildiko Kmecz Bela Simandi Tetrahedron : Asymmetry , 2005 , 16 , 3841-3847). That is, using a PPL enzyme to the present (-) - (2 R, 3 S) - has not been reported effective dynamic partitioning of methanol-oxiran-2-yl.

It is an object of the present invention to provide a process for the stereoselective preparation of (2R, 3S)-(3- (substitutedmethyl) -oxirane-2-yl) methanol.

The present invention provides a method for preparing the compound of formula (2), which is an optical isomer comprising the step of hydrolyzing the compound of formula (1) which is a racemate with the enzyme PPL (porcine pancreatic lipase) in the reaction solvent.

[Formula 1]

(2)

In this formula,

Ac means an acetyl group,

X is C1 to C6 alkanes, C2 to C3 alkenes, benzene or naphthalene, wherein alkanes and alkenes are unsubstituted or substituted one or more with fluoro, chloro, bromine, iodine, nitro, benzene, naphthalene, preferably Preferably they are C1-C6 alkanes substituted with one or more of fluoro, chloro, bromine, iodine, nitro, benzene, naphthalene, more preferably benzyl (Bn).

In the preparation method of the present invention, the reaction solvent may be an organic solvent having various polarities, and xylene is preferred. More preferred reaction solvent may be a mixed solvent of a buffer and an organic solvent. Preferred buffers used in the present invention are phosphate buffers with pH = 7.2, and are hydrolyzed by lipase catalysts to [2,2,1] -bicyclic oxoester intermediates when the reaction environment is gradually oxidized ([2,2,1]. ] to prevent conversion to 2-methyl-D-erythritol via rearrangement of bicyclic orthoester intermediates. Therefore, the use of the mixed solvent of the buffer and the organic solvent has an effect of inhibiting further cleavage of the oxirane ring, which is a product, by neutralizing the acidic product immediately, rather than simply using the organic solvent alone.

The mixing ratio of the buffer and the organic solvent can be varied in various ways as long as the object of the present invention is satisfied. For example, the buffer and the organic solvent may be mixed in a volume ratio of 1:10 to 10: 1, and a preferred volume ratio is 1: 1 volume ratio (v / v).

In the mixed solvent of the buffer and the organic solvent used in the present invention, the log P value related to the polarity of the organic solvent is preferably 3.00 to 3.50. Where log P is defined as the logarithm of the partition coefficient of the solvent based on a two-phase system of 1-octanol and water, and represents polarity. The log P value of these organic solvents is an important parameter that is consistent with the ratio of hydrolysis by PPL enzyme. In other words, the larger the log p value, the more polar the solvent.

In the mixed solvent of the buffer and the organic solvent, the organic solvent is more preferably a nonpolar solvent such as xylene, cyclohexane, hexane.

In the mixed solvent of the buffer and the organic solvent of the present invention, the buffer may be used as long as it is a buffer used for a general enzyme reaction. For example, there is a buffer solution using phosphate, citric acid, sodium tetraborate, and the like, and preferably a buffer solution using phosphate.

The pH of the buffer which can be used in the present invention is preferably in the range of not affecting the activity of the PPL enzyme used in the present invention, pH = 4.0 to 10.5, more preferably 6.5 to 7.9, more preferably pH 7.2. Do.

The reaction of the present invention may be carried out at 0 ° C ~ 60 ° C, more preferably 10 ° C to 35 ° C. If the reaction temperature is too low, the reaction rate is slowed. If the reaction temperature is too high, denaturation of the enzyme occurs. Preferred reaction temperatures are about 25 ° C.

In another aspect, the present invention provides a method for preparing a compound of formula (3) comprising the step of preparing a compound of formula (2) of the present invention and the oxidation of the compound of formula (2) to produce a compound of formula (3).

[Formula 3]

Where

X is C1 to C6 alkanes, C2 to C3 alkenes, benzene or naphthalene, wherein alkanes and alkenes are unsubstituted or substituted one or more with fluoro, chloro, bromine, iodine, nitro, benzene, naphthalene, preferably Crab is C1 to C6 alkanes substituted with at least one of fluoro, chloro, bromine, iodine, nitro, benzene and naphthalene, more preferably benzyl.

The method for oxidizing the compound of formula 2 to the compound of formula 3 may use a known method for oxidizing the primary alcohol with aldehyde. For example, there is a method using Swern oxidation, PCC oxidation, and Dess-Martin periodinane, and preferably, a method using Dess-Martin periodinane is used. Here, Dess-Martin periodinane is described in J. Org . Chem . It is manufactured by the method described in 1999 , 64 , 4537-4538.

The present invention is a dynamic isomerization of the racemate cis- (3- (substitutedmethyl) oxiran-2-yl) methylacetate using PPL enzyme, which is an optical isomer (2R, 3S)-(3- (substitutedmethyl) -Oxirane-2-yl) methanol can be obtained in high yield, high purity.

The invention is further illustrated by the following examples. The following non-limiting examples merely illustrate the preparation of the invention and do not limit the scope of the invention. The production method according to the invention is characterized in that it can be easily applied to general industrial production.

Samples and PPL used below were purchased from Aldrich and Sigma. THF (Tetrahydrofuran) and ethyl ether were used by distillation under argon (Ar) gas using sodium metal and benzoquinone, and dichloromethane, acetonitrile and toluene were distilled using calcium hydride. Other solvents were best purchased from Aldrich, JT Baker, and Fisher. Enzyme reaction was carried out in JEIO TECH (Korea) incubatory orbital shaker SI-300R at 160 rpm at 25 ℃. Conversion rate and enantiomeric excess were determined by Chiral HPLC (High Performance Liquid Chromatography) analysis using Hewlett-Packard 1200, liquid chromatograph (CHIRALCEL OD). Optical rotations were measured with a JASCO DIP-1000 digital polarimeter, and NMR spectra were measured using CDCl ₃ as a solvent and Bruker Avance 400 spectrometer. Chemical shifts were calculated as ppm values relative to the value of tetramethylsilane (TMS). Coupling constants were reported in hertz and positive electrospray ionization (ESI ⁺ ) was measured using a Hewlett-Packard spectrometer. IR spectra were measured using a JASCO 420 FT-IR spectrometer. Thin layer chromatography (TLC) was performed using a precoated silica gel plate (Merck 60 F ₂₅₄ ), and fresh column chromatography was performed on silica gel 60 (Merck, 0.040-0.063 mm, 230-400 mesh). Was used, and hexane and ethyl acetate were used as the developing solvent.

< Production Example > Race Semi Chain Sheath -3- ( Benzyloxymethyl ) Oxirane -2 days) Methyl acetate ( Formula 1  Compound)

To a solution of cis-4-benzyloxy-but-2-en-1-ol (2,425 mg, 13.61 mmol) CH ₂ Cl ₂ (40 ml) NaHCO ₃ (2,172 mg, 25.85 mmol) at once at 0 ^o C After adding and stirring for 5 minutes, m CPBA (2,818mg, 16.33mmol) was added thereto and allowed to react for 3 hours while raising the temperature to room temperature. The reaction was stopped with saturated aqueous sodium hydrogen carbonate solution (25 ml) and the reaction solution was diluted with CH ₂ Cl ₂ . The organic layer was separated and the aqueous layer was extracted three times with CH ₂ Cl ₂ . The collected organic layers were dried over brine and anhydrous MgSO ₄ , the solvent was evaporated in vacuo and the residue was separated by fresh column chromatography ( n -hexane: EtOAc = 3: 1v / v) to oxirane. The compound was obtained as a colorless oil in 78% yield. To a CH ₂ Cl ₂ (40 ml) solution of oxirane compound (2,062 mg, 10.61 mmol), pyridine (1.28 ml, 15.94 mmol), DMAP (259.64 mg, 2.12 mmol) and (CH ₃ CO) ₂ O (1.30 ml, 12.74 mmol) was added at 0 ° C. and stirred at rt for 6 h. The mixture was diluted with dichloromethane (40 ml) and washed with water. After collecting the organic layer and evaporating the solvent in vacuo, the residue was subjected to fresh column chromatography ( n- hexane: EtOAc = 4: 1v / v) to yield 99% yield of the title compound, acetylated racemic epoxide compound ( 1,318 mg) [ ¹ H-NMR (400 MHz, CDCl ₃ ) δ: 7.31 (m, 5H) 4.56 (d, J = 7.2 Hz, 2H) 4.39 (m, 1H) 3.95 (q, J = 12.32, J = 6 Hz, 1H) 3.75 (m, 1H) 3.52 (m, 1H) 3.13 (m, 2H) 2.06 (m, 3H)].

Example 1 Preparation of (2R, 3S) -3- (benzyloxymethyl) oxan-2-yl) methanol in a pure organic solvent

To put the cis-3- (benzyloxymethyl) oxirane-2-yl) methyl acetate (100 mg) which is the racemate of the compound 1 prepared in the preparation example in the solvent shown in Table 1 below, add the enzyme PPL (100 mg), At 25, it was reacted for 3 or 48 hours (see Scheme 1).

Enzyme according to the reaction solvent to determine how the nature of the organic solvent and the propensity of the enzyme related to the solubility of the substrate in the organic solvent affect the conversion rate and E value of hydrolysis by PPL The reactivity of The results of the reaction are summarized in Table 1.

Scheme 1

(Bn in the above scheme means benzyl group)

Table 1 Hydrolysis Results of PPL-Enzyme in Pure Organic Solvents

^a Reference: Biotechnology and Bioengineering 1987, 30, (1), 81-87

^b Conversion rate was determined based on HPLC analysis using a chiral column.

^The optical purity was determined based on the results of HPLC analysis using a ^c chiral column.

^d E = ln [(1-ee _s ) / {1+ (ee _s / ee _p )}] / ln [(1 + ee _s ) / {1+ (ee _s / ee _p )}]

Table 1 shows the approximate index of the conversion of PPL-enzyme hydrolysis and log P in 11 pure organic solvents. Hydrolysis of racemic compound 1 by PPL enzyme was observed in various ways depending on the type of solvent. The type of organic solvent was found to have a very important effect on the E value of racemic compound 1, and log P was found to have a significant effect on the conversion and enantioselectivity. The results of numbers 1 to 11 in Table 1 showed that the optical purity of the product was very high in fat-soluble solvents such as hexane (log P = 3.50), cyclohexane (log P = 3.20), and xylene (log P = 3.10). In particular, when reacted with a racemic compound 1 in xylene at PPL E value in the initial 3 hours, although with high 1.78, 48 hours of reaction, exhibits a 95.9ee%, of 67.5 and E value conversion rate of 59.45% pure organic Xylene showed the best effect in PPL reaction with solvent.

In addition, E value of acetone, a polar solvent, increased steadily from E = 5.73 (3 hours) to E = 12.67 (48 hours) .The tetrahydrofuran, an ether type with a low log P value, had an E value of 13.77 after 48 hours. This was. In addition, dichloromethane with a log P value similar to tetrahydrofuran showed higher E values (4.83 at 3 hours, 13.77 at 48 hours) and conversion (28.93% at 3 hours, 84.34% at 48 hours) than tetrahydrofuran. Indicated.

Example 2 Reaction in Buffer-Organic Solvent Mixture

100 mg of cis-3- (benzyloxymethyl) oxiran-2-yl) methylacetate, which is the racemate of Compound 1 prepared in Preparation Example, was added to 200 ml of a solvent in which the solvent and the buffer shown in Table 2 were mixed in a 1: 1 volume ratio. 100 mg of PPL was added and reacted at 25 ° C. for 3 hours or 48 hours (see Scheme 2), except that the buffer used a phosphate buffer of pH = 7.2.

The organic solvent-buffer (1: 1, v / v) mixture neutralizes the hydrolyzed product (carboxylic acid) to inhibit further cleavage of the oxirane ring, and the thermodynamic water activity (a _w ) Adjust to the maximum with the buffer solution containing the salt. Therefore, the present inventors have discussed how the nature of the organic solvent in the water-organic solvent system and the propensity of the enzyme related to the solubility of the substrate in the organic solvent affect the conversion rate and E value of hydrolysis by PPL. To find out, we examined the reactivity of the enzyme according to the reaction solvent.

Scheme 2

Table 2 Hydrolysis Results of PPL-Enzyme in Buffer and Organic Solvents (1: 1v / v)

^a Reference Biotechnology and Bioengineering 1987, 30, (1), 81-87

^b Conversion rate was determined based on HPLC analysis using a chiral column.

^The optical purity was determined based on the results of HPLC analysis using a ^c chiral column.

^d E = ln [(1-ee _s ) / {1+ (ee _s / ee _p )}] / ln [(1 + ee _s ) / {1+ (ee _s / ee _p )}]

Table 2 shows the approximate indicators of the correlation between PPL-enzyme hydrolysis and log P in the solvent mixture of 10 organic solvents and buffers in a 1: 1 volume ratio. According to Table 2, the log P value of the solvent and the stereoselectivity of the hydrolysis of the PPL enzyme in the buffer-organic solvent are not directly proportional, but xylene, cyclohexane and hexane (numbers 8 to 10, log P are 3.10 to 3.50 Value) is very effective for hydrolysis of racemic compound 1 by PPL. In particular cyclohexane (number 9) showed the highest 99.5ee% and E (> 200) values among these three solvents after 48 hours reaction. Xylene and hexane are also effective for the dynamic splitting of hydrolysis by PPL-enzyme of racemic chemical 1 since the E value exceeds 100 (153.91 and 129.95) after 48 hours reaction. In particular, both of these solvents also had excellent stereoselectivity after 3 hours of reaction (95.3%, 89.0%), and after 48 hours of reaction, the ee% value increased steadily to show values of 98.0% and 96.2%.

In addition, ethyl ether and toluene showed good results in the first 3 hours of the reaction (numbers 6 and 7), and methanol and acetone mixed very well with water also had appropriate E values (numbers 2 and 4).

Claims (11)

The compound of formula 1, which is a racemate, is synthesized with an enzyme PPL (porcine pancreatic lipase) in a solvent or xylene in which an organic solvent having a log P value of 3.00 to 3.50 related to the polarity of the organic solvent and a buffer are mixed in a 1: 1 volume ratio. Method for preparing a compound of formula (2) is an optical isomer comprising the step of resolving and dynamic splitting: [Formula 1]

(2)

In this formula, Ac means an acetyl group, X is C1 to C6 alkanes, C2 to C3 alkenes, benzene or naphthalene, wherein alkanes and alkenes are unsubstituted or substituted one or more with fluoro, chloro, bromine, iodine, nitro, benzene, naphthalene. The process of claim 1 wherein X is benzyl. delete delete delete delete The process according to claim 1, wherein the organic solvent is xylene, cyclohexane or hexane. 8. The method of claim 1 or 7, wherein the buffer is phosphate buffer. The method of claim 8, wherein the pH of the buffer is 6.5 to 7.9. The method of claim 9, wherein the pH of the buffer is 7.2. The manufacturing method of any one of Claims 1, 2, and 7 whose reaction temperature is 25 degreeC.