The asymmetric tandem oxa-Michael-aldol reaction of salicylic aldehyde derivatives with α,β-unsaturated aldehydes catalyzed by a chiral amine/chiral acid organocatalytic system was investigated. The organocatalytic system of (S)-diphenylpyrrolinol trimethylsilyl ether with chiralshiftreagent (S)-Mosher acid presented a synergistic effect in the improvement of reaction performance and offered an efficient
研究了水杨醛衍生物与手性胺/手性酸有机催化体系催化的α,β-不饱和醛的不对称串联氧杂-迈克尔-阿尔道反应。(S)-二苯基吡咯啉三甲基甲硅烷基醚与手性转移剂(S)-Mosher酸的有机催化体系在提高反应性能方面具有协同作用,并在转化中提供了有效的空间效应。串联的oxa-Michael-aldol反应以高收率(最高90%)和优异的ee值(最高99%)进行,得到相应的色烯衍生物。还通过1 H NMR研究了原位形成的手性铵盐的结构及其相应的机理。
Catalytic Enantioselective Domino Oxa-Michael/Aldol Condensations: Asymmetric Synthesis of Benzopyran Derivatives
The first direct organocatalyticasymmetricdomino oxa-Michael/aldol condensation reaction is presented. The unprecedentedly simple, chiral, pyrrolidine-catalyzed asymmetricdominoreactions between salicylic aldehyde derivatives and alpha,beta-unsaturated aldehydes proceed with high chemo- and enantioselectivities to give the corresponding chromene-3-carbaldehyde derivatives in high yields and with
Enantioselective organocatalytic synthesis of the chiral chromenes by domino oxa-Michael-aldol reaction
作者:Shrikant S. Pendalwar、Avinash V. Chakrawar、Sudhakar R. Bhusare
DOI:10.1016/j.cclet.2017.09.058
日期:2018.6
found to be an efficient catalyst for the facile synthesis of substituted 2-aryl-2H-chromenes-3-carbaldehyde. We envisioned that the iminium interaction between chiral amino catalysts and α,β-unsaturated carbonyl group was beneficial along with thiourea group as hydrogen bond donor, heterocyclic amines as general base in the domino oxa-Michael-aldol reaction. This catalytic system provided the products