Systematic methodology for the development of biocatalytic hydrogen-borrowing cascades: application to the synthesis of chiral α-substituted carboxylic acids from α-substituted α,β-unsaturated aldehydes
作者:Tanja Knaus、Francesco G. Mutti、Luke D. Humphreys、Nicholas J. Turner、Nigel S. Scrutton
DOI:10.1039/c4ob02282c
日期:——
catalyze the asymmetric reduction of activated carbon–carbon double bonds. In particular, α,β-unsaturated carbonyl compounds (e.g. enals and enones) as well as nitroalkenes are rapidly reduced. Conversely, α,β-unsaturated esters are poorly accepted substrates whereas free carboxylic acids are not converted at all. The only exceptions are α,β-unsaturated diacids, diesters as well as esters bearing an
烯还原酶 (ER) 是黄素依赖性酶,可催化活性碳-碳双键的不对称还原。特别是 α,β-不饱和羰基化合物(例如enals 和 enones) 以及硝基烯烃被迅速还原。相反,α,β-不饱和酯是难以接受的底物,而游离羧酸根本不被转化。唯一的例外是 α,β-不饱和二酸、二酯以及在 α-或 β-位带有吸电子基团的酯。在这里,我们提出了一种替代方法,该方法具有直接获得各种手性 α-取代羧酸的普遍适用性。这种方法在同时进行的还原-氧化生物催化级联中结合了两种酶,即 ER 和醛脱氢酶 (Ald-DH)。该策略具有几个优点,因为起始材料是 α-取代的 α,β-不饱和醛,这是一类对烯烃部分的还原具有极强反应性的化合物。例如葡萄糖、甲酸盐)是必需的,因为用于第一还原步骤的氢化物在第二氧化步骤中释放。这样的过程被定义为借氢级联。该方法具有广泛的适用性,因为它成功地应用于手性取代的氢化肉桂酸、脂肪酸、杂环化合物甚至