Pd-Catalyzed C–S Activation for [3 + 3] Annulation of 2-(Methylthio)benzofuran-3-carboxylates and 2-Hydroxyphenylboronic Acids: Synthesis of Coumestan Derivatives
作者:Jingxin Liu、Yingjie Liu、Wenting Du、Ying Dong、Jun Liu、Mang Wang
DOI:10.1021/jo400984h
日期:2013.7.19
Pd-catalytic C-S activation was successfully applied to initiate the cross-coupling of (2-methylthio-3-ester)benzofurans with 2-hydroxyphenylboronic acids and sequential intramolecular transesterification process under Liebeskind-Srogl conditions. Thus, a novel [3 + 3] annulation strategy for efficient synthesis of coumestan derivatives has been developed from readily available starting materials.
Synthesis of Coumestan Derivatives via FeCl<sub>3</sub>-Mediated Oxidative Ring Closure of 4-Hydroxy Coumarins
A concise and efficient approach to the syntheses of coumestan analogues has been developed. The underpinning strategy involves a FeCl3-mediated direct intramolecular oxidative annellation of 4-hydroxy-3-phenyl-2H-chromen-2-one derivatives. Utilizing this synthetic protocol, a variety of coumestan derivatives were conveniently obtained from readily available reagents.