15-Cl2-DHTP–boron complex catalyst for the asymmetric Diels–Alder cycloaddition of 2′-hydroxychalcones and dienes was developed and tested. The resulting cyclohexenes with three chiral centers were obtained in high yields (up to 98%) with excellent stereoselectivities (up to >20:1 endo/exo, >99% ee). This catalytic system features high efficiency, broad substrate scopes, and mild reaction conditions. In
(小号)-2,15-CL 2 -DHTP -硼为2'-hydroxychalcones和二烯不对称狄尔斯-阿尔德环加成配合物催化剂进行开发和测试。得到的具有三个手性中心的环己烯以高收率(高达98%)和优异的立体选择性(高达> 20:1 end / exo,> 99%ee)获得。该催化系统具有高效,广泛的底物范围和温和的反应条件的特点。另外,进行了DFT研究以解释不对称诱导的立体化学过程。
Ionic liquid mediated Cu-catalyzed cascade oxa-Michael-oxidation: efficient synthesis of flavones under mild reaction conditions
作者:Zhiyun Du、Huifen Ng、Kun Zhang、Huaqiang Zeng、Jian Wang
DOI:10.1039/c1ob06209c
日期:——
Flavonoids are a class of natural products, found in a wide range of vascular plants and dietary components. Their low toxicity and extensive biological activities, including anti-cancer and anti-bacterial, have made them attractive candidates to serve as therapeutic agents for many diseases. Herein, we disclose a highly efficient synthetic method of CuI-catalyzed cascade oxa-Michael-oxidation, using chalcones as substrates, mediated by the ionic liquid [bmim][NTf2] at a low temperature. This efficient synthetic method has demonstrated high synthetic utility and can afford flavones in good to high yields (up to 98%).