Asymmetric synthesis of β-substituted Baylis–Hillman products via lithium amide conjugate addition
作者:Alexander Chernega、Stephen G. Davies、Dirk. L. Elend、Christian A.P. Smethurst、Paul M. Roberts、Andrew D. Smith、G. Darren Smyth
DOI:10.1016/j.tet.2007.05.015
日期:2007.7
products has been developed. This procedure involves the diastereoselective conjugate addition of lithium (R)-N-methyl-N-(α-methylbenzyl)amide to an α,β-unsaturated ester to generate an N-protected β-amino ester in high de. Subsequent asymmetric aldol reaction via deprotonation with LDA, transmetallation with B(OMe)3 and addition of an aldehyde gives a range of syn-aldol products in moderate to high de
已经开发出了三步协议,用于一系列β-取代的Baylis-Hillman产品的不对称合成。该方法涉及将锂(R)-N-甲基-N-(α-甲基苄基)酰胺非对映选择性共轭加成至α,β-不饱和酯,以高纯度产生N-保护的β-氨基酯。随后的不对称醛醇缩合反应通过与LDA进行去质子化,与B(OMe)3的金属转移和醛的加入,产生了一系列中等至高de的顺式醛醇缩合产物。该净化SYN-羟醛产品达到均质,然后进行串联N-氧化和Cope消除,从而以高收率和高收率获得了所需的β-取代的Baylis-Hillman产品。