Wilson Jonathan E, Casarez Anthony D, MacMillan David W C
Merck Center for Catalysis, Princeton University, Princeton, New Jersey 08544, USA.
J Am Chem Soc. 2009 Aug 19;131(32):11332-4. doi: 10.1021/ja904504j.
The first enantioselective organocatalytic alpha-nitroalkylation of aldehydes has been accomplished. The aforementioned process involves the oxidative coupling of an enamine intermediate, generated transiently via condensation of an amine catalyst with an aldehyde, with a silyl nitronate to produce a beta-nitroaldehyde. Two methods, one that furnishes the syn beta-nitroaldehyde and a second that provides access to the anti isomer, have been developed. Data are presented to support a hypothesis that explains this phenomenon in terms of a silyl group-controlled change in mechanism. Finally, a three-step procedure for the synthesis of both syn- and anti-alpha,beta-disubstituted beta-amino acids is presented.
醛的首例对映选择性有机催化α-硝基烷基化反应已完成。上述过程涉及通过胺催化剂与醛的缩合瞬时生成的烯胺中间体与硅基硝酮的氧化偶联，以生成β-硝基醛。已开发出两种方法，一种用于制备顺式β-硝基醛，另一种用于制备反式异构体。给出的数据支持了一个假说，该假说根据硅基控制的机理变化来解释这一现象。最后，给出了一种合成顺式和反式α,β-二取代β-氨基酸的三步方法。
