Preparation Of CHIRAL4-CHLORINE-3-Hydroxy Ethyl Butyrate By Biotransformation

In this paper, we made detailed study about preparation of chiral4-chlorine-3-hydroxy ethyl butyrate by biotransformation.Chiral4-chlorine-3-hydroxy ethyl butyrate is a very important chiral drug intermediates. It has been widely used in the synthesis of pharmaceutical and agricultural chemical.(S)-4-chlorine-3-hydroxy ethyl butyrate is an important chiral building block of reductase inhibitors HMG-CoA. At the begining of this paper,(S)-4-chlorine-3-hydroxy ethyl butyrate was produced by asymmetric reduction of COBE through optimum strain Rhodotorula qlutinis2.102. The optimum reduction condition are as follows:pH7.0, temperature35℃, reaction time24h, substrate concentration20g/L, cell concentration180g/L,shaking speed180rpm, the optimum addition amount of allyl alcohol as inhibitor3%(v/v). Conversion and enantiometric excess of (S)-4-chlorine-3-hydroxy ethyl butyrate reached100%and98.6%. And then studied the amplification, the result is ideal. The average conversion rate is99.967%and the average ee. of (R)-CHBE is98.567%.Next, preparation of (R)-4-chlorine-3-hydroxy ethyl butyrate by microbial catalysis carbonyl reduction and resolution using the lipase coupling method was studied, enantiometric excess of (R)-4-chlorine-3-hyd roxy ethyl butyrate reached99%min.(R)-4-chlorine-3-hydroxy ethyl butyrate can be used to synthesize L-carnitine and1,4-dihy-dropyridine-type-pblocker.The study result showed that the reducing capacity of bacterial strain Saccharomyces cerevisiae2.53is strong. The optimum reduction condition are as follows:substrate concentration15g/L, cell concentration180g/L, temperature30℃, reaction time36h, PH7.0, shaking speed180rpm. Conversion and enantiometric excess of (R)-4-chlorine-3-hydroxy ethyl butyrate reached100%and81.6%.The enantiometric excess of (R)-4-chlorine-3-hydroxy ethyl butyrate was not ideal, we took the4-chlorine-3-hydroxy ethyl butyrate which had86.1%ee. as substrate to study. Transesterification reaction under the catalysis of lipase3#was studied. Acetic acid vinyl ester was Choosed as acyl donors and solvent in the process. Lipase3#was selected as the best one. The optimum reaction condition of enzymatic resolution are as follows: substrate concentration300mmol/L, the quantity of enzyme10mg, temperature40℃, shaking speed150rmp. Enantiometric excess of (R)-4-chlorine-3-hydroxy ethyl butyrate reached99%min.Then, preparation of CHBE from4-chloro-3-(1-oxobutoxy)-butanoic acid ethyl ester (CABB) by lipase2#hydrolysis reaction was studied. CABB was from esterification reaction between butyric anhydride and4-chlorine-3-hydroxy ethyl butyrate which had86.1%ee.The optimum condition of hydrolysis reaction are as follows:the quantity of enzyme15mg, substrate concentration400mmol/L, temperature45℃, shaking speed200rmp. Enantiometric excess of (R)-4-chlorine-3-hydroxy ethyl butyrate reached99%min.