An investigation of the scope of the 1,7-electrocyclization of α,β:γ,δ-conjugated azomethine ylides
摘要:
Substituents on the diene component have little influence on the periselectivity of the cyclizations of alpha,beta:gamma,delta-conjugated azomethine ylides, with 1,7-electrocyclizations predominating. In some cases, subtle changes to these substituents can, however, influence the product formed, through their effect on the relative energies of the transition states for the 1,5- (6 pi) and 1,7-electrocyclization (8 pi) processes. The most striking changes in periselectivity occur for phenylethenyl-substituted azomethine ylides 3d-f, which can give either a pyrroline 4d,f or dihydrobenzazepine 6e, depending upon the alkene configuration. (C) 2014 Elsevier Ltd. All rights reserved.
描述了一种新颖、简单且无金属的串联方法,通过酸催化环氧化物重排和有机催化羟醛缩合过程合成α-取代( E )-α,β-不饱和醛衍生物。该转化在温和条件下具有广泛的底物范围,包括含有不同官能团的环氧化物和醛,从而产生中等到高产率的所需产物。最终,大规模反应和一些生物活性分子的合成被用来证明所开发方法的潜在适用性。