Direct Visible-Light-Excited Asymmetric Lewis Acid Catalysis of Intermolecular [2+2] Photocycloadditions
作者:Xiaoqiang Huang、Taylor R. Quinn、Klaus Harms、Richard D. Webster、Lilu Zhang、Olaf Wiest、Eric Meggers
DOI:10.1021/jacs.7b04363
日期:2017.7.12
A reaction design is reported in which a substrate-bound chiral Lewisacid complex absorbs visible light and generates an excited state that directly reacts with a cosubstrate in a highly stereocontrolled fashion. Specifically, a chiral rhodium complex catalyzes visible-light-activated intermolecular [2+2] cycloadditions, providing a wide range of cyclobutanes with up to >99% ee and up to >20:1 d.r
报道了一种反应设计,其中底物结合的手性路易斯酸配合物吸收可见光并产生激发态,该激发态以高度立体控制的方式直接与共底物反应。具体来说,手性铑配合物催化可见光激活的分子间 [2+2] 环加成,提供各种环丁烷,其 ee 高达 >99%,dr 高达 >20:1 值得注意的是能够产生邻位全-碳四元立体中心,包括分子间形式的螺中心。
Enantioselective Radical Methods for Lactone Synthesis: Use of Unprotected Haloalcohols as Radical Precursors
作者:Mukund P. Sibi、Miguel A. Guerrero
DOI:10.1055/s-2005-865319
日期:——
We have developed an efficient free radical method for the synthesis of enantioenriched 6- and 7-membered lactones in one synthetic operation.