Biocatalytic Asymmetric Michael Additions of Nitromethane to α,β-Unsaturated Aldehydes via Enzyme-bound Iminium Ion Intermediates
作者:Chao Guo、Mohammad Saifuddin、Thangavelu Saravanan、Masih Sharifi、Gerrit J. Poelarends
DOI:10.1021/acscatal.9b00780
日期:2019.5.3
found to efficiently promote asymmetric Michael additions of nitromethane to various α,β-unsaturated aldehydes to give γ-nitroaldehydes, important precursors to biologically active γ-aminobutyric acids. High conversions, high enantiocontrol, and good isolated product yields were achieved. The reactions likely proceed via iminium ion intermediates formed between the catalytic Pro-1 residue and the α,β-unsaturated
4-草酸巴豆酸酯互变异构酶(4-OT)利用N末端脯氨酸作为主要催化残基,通过酶结合的烯胺中间体促进多个混杂的C–C键形成反应。在这里,我们表明该酶的活性位点可引起进一步的合成有用的催化混杂。具体而言,发现4-OT的F50A突变体可有效地促进硝基甲烷向各种α,β-不饱和醛的不对称迈克尔加成反应,从而生成γ-硝基醛,这是生物活性γ-氨基丁酸的重要前体。实现了高转化率,高对映体控制和良好的分离产物收率。反应可能是通过催化Pro-1残基和α,β-不饱和醛之间形成的亚胺离子中间体进行的。此外,通过三个4-OT(F50A)催化反应的级联反应,然后进行酶促氧化步骤,可以将三个简单构件中的γ-硝基羧酸组装到一个罐中。我们的结果桥接了有机催化和生物催化,它们强调了酶的混杂在制备重要手性合成子中的潜力。