We examined ten strains of cultured whole-cell yeasts for the asymmetric reduction of commercially available ethyl 2-oxocyclohexanecarboxylate, and found that the (1S,2S)-stereoisomer of ethyl 2-hydroxycyclohexanecarboxylate was the major stereoisomer produced by Williopsis californica JCM 3600. The ethyl group of the ester was then substituted with a benzyl group with low volatility and increased hydrophobicity to facilitate the isolation of the expected product. Incubation with W. californica furnished benzyl (1S,2S)-2-hydroxycyclohexanecarboxylate (>99.9% ee) in 51.0% yield together with its (1R,2S)-isomer (>99.9% ee) in 35.4% yield. Upon treatment of the same substrate bearing the benzyl ester with a screening kit of purified overexpressed carbonyl reductases (Daicel Chiralscreen^® OH), two enzymes (E031, E078) furnished the (1R,2S)-isomer as the major product. With another enzyme (E007), the (1S,2R)-isomer was obtained, but its ee was very low (25.6%). The highly enantiomerically enriched (1S,2S)-isomer obtained by W. californica was transformed to the (1S,2R)-isomer (>99.9% ee), whose availability until now has been low, in 43.3% yield over two steps involving tosylation and subsequent inversive attack with tetrabutylammonium nitrite.

我们检查了十株培养的全细胞酵母的不对称还原市售的2-氧代环己烷甲酸乙酯，发现2-羟基环己烷甲酸乙酯的（1 S，2 S）-立体异构体是由加利福尼亚州柳产JCM 3600产生的主要立体异构体然后用低挥发性和增加的疏水性的苄基取代酯的乙基，以促进预期产物的分离。与加利福尼亚州W. californica一起温育提供了苄基（1 S，2 S）-2-羟基环己烷羧酸酯（> 99.9％ee）及其收率（1 R，2 S）达到51.0％-异构体（> 99.9％ee），收率35.4％。处理后在同一基板轴承用纯化过表达的羰基还原酶的筛选试剂盒（大赛璐Chiralscreen苄基酯的^® OH），两种酶（E031，E078）得到（1 - [R，2小号） -异构体为主要产物。与另一种酶（E007），所述（1小号，2 - [R ），得到异构体，但其ee值是非常低的（25.6％）。由W. californica获得的高度对映体富集的（1 S，2 S）-异构体被转化为（1 S，2 R-异构体（> 99.9％ee），到目前为止，其可用性一直很低，分两步进行，包括甲苯磺酸化和随后的亚硝酸四丁铵逆向攻击，收率达43.3％。