P(NMe_(2))_(3)介导1,2-二羰基化合物与α,β-不饱和酮的[1+4]环化反应及多取代2,3-二氢呋喃的合成

Synthesis of Polysubstituted 2,3-Dihydrofurans via P(NMe_(2))_(3)-Mediated[1+4]Annulation of 1,2-Dicarbonyl Compounds withα,β-Unsaturated Ketones

在P(NMe_(2))_(3)作用下,1,2-二羰基化合物与α,β-不饱和酮顺利发生分子间[1+4]环化反应,生成带有全碳季碳中心的多取代2,3-二氢呋喃类化合物,从而以较高的收率及较宽的底物范围提供了合成该类化合物的新方法.在某些情况下,[1+2]环化反应竞争发生生成多取代的环丙烷化合物.借助密度泛函理论(DFT)计算手段,讨论了反应机理及有关[1+2]环化反应与[1+4]环化反应的化学选择性.

A[1+4]annulation of 1,2-dicarbonyl compounds withα,β-unsaturated ketones has been readily realized under the mediation of P(NMe_(2))_(3),producing polysubstituted 2,3-dihydrofurans bearing a quaternary carbon center in fair to good yields with a broad substrate scope.This reaction accordingly constitutes a new synthetic method for such compounds.In some cases,a[1+2]annulation reaction competitively occurs,delivering polysubstituted cyclopropanes.With the aid of density functional theory(DFT)calculation,a plausible mechanism for the[1+4]annulation and the chemoselectivity between[1+2]and[1+4]annulations has been discussed.