作者:Christoph Kobler、Franz Effenberger
DOI:10.1016/j.tetasy.2004.10.010
日期:2004.11
stereoselectivity of hydroxynitrile lyases (HNLs) catalyzed addition of HCN to a variety of monosubstituted cyclopentanones yielding the corresponding cyanohydrins is presented. With PaHNL from bitter almond as catalyst, the HCN addition to 2-alkyl cyclopentanones 1b–d is highly (R)-selective, leading to the cis-(1R,2S)- and trans-(1R,2R)-diastereomers. The addition to the sterically less demanding methyl compound
进行了系统研究的羟腈裂解酶(HNLs)催化HCN加成到各种单取代的环戊烷生成相应的氰醇的立体选择性。以苦杏仁中的PaHNL为催化剂,在2-烷基环戊酮1b - d中的HCN加成高度(R)选择性,导致顺式-(1 R,2 S)-和反式-(1 R,2 R) -非对映异构体。在空间上要求较低的甲基化合物1a中的添加选择性低得多。随着MeHNL从木薯,预期(小号对具有较大取代基的环戊酮1c - d而言,HCN加成的选择性非常高,但仅对顺式-(1 S,2 R)-非反式-(1 S,2 S)-非对映异构体。对于MeHNL催化的外消旋烷基2-氧代环戊烷羧酸酯4a和4b的HCN加氢,观察到动态动力学拆分。通过酮-烯醇互变异构体的连续平衡和酮4(R)-对映异构体的优选酶促转化导致顺式-(1 R,> 2S)-非对映异构体,产率> 50%。合成氰醇的绝对构型由X-射线晶体学确定ö - p -bromobenzoyl衍生物。