Multienzymatic Stereoselective Reduction of Tetrasubstituted Cyclic Enones to Halohydrins with Three Contiguous Stereogenic Centers
作者:Silvia Venturi、Elisabetta Brenna、Danilo Colombo、Marco W. Fraaije、Francesco G. Gatti、Piero Macchi、Daniela Monti、Milos Trajkovic、Emilio Zamboni
DOI:10.1021/acscatal.0c04097
日期:2020.11.6
tetrasubstituted alkenes with transition-metal catalysts is a challenging reaction, especially for substrates bearing a halide substituent. We describe a two-step multienzymatic reduction of a series of α-halo β-alkyl tetrasubstituted cyclic enones, affording halohydrins with three contiguous stereogenic centers, in good yield and with a high stereoselectivity. The reduction is catalyzed by a stereospecific ene-reductase
共轭四取代烯烃与过渡金属催化剂的不对称氢化是一个具有挑战性的反应,特别是对于带有卤化物取代基的底物。我们描述了一系列α-卤代β-烷基四取代的环烯酮的两步多酶还原反应,提供了具有三个连续的立体中心,具有良好收率和高立体选择性的卤代醇。还原反应由立体特异性烯键还原酶(OYE2-3或NemA)和高对映选择性醇脱氢酶(ADH)催化。使用两种对映异构的ADH允许控制非对映选择性。产品的绝对立体化学构型已通过对单晶结构的分析来确定(Flack参数)。对映体过量(ee)已通过将产品用(R)莫舍尔酸衍生化来确定。最后,我们也将我们的方法扩展到了非卤代底物上:α-甲基酮异佛尔酮被两种不同的对映异构烯还原酶(黄素单核苷酸依赖性和F 420依赖性)还原,从而得到ee > 98%的饱和酮的每个对映异构体。