Enantioselective Radical Hydroacylation of α,β-Unsaturated Carbonyl Compounds with Aldehydes by Triplet Excited Anthraquinone
Yao Luo, Wei Qi, Liangkun Yang, Yuqiao Zhou, Weidi Cao, Zhishan Su, Xiaohua Liu, Xiaoming Feng
Abstract
The synthesis of chiral ketones has been a long focus of chemistry research. Enantioselective radical hydroacylation, as a useful strategy to access various chiral ketones, was restricted to the reaction with β-substituted alkenes, in which a β-stereocenter was generated via a stereocontrolled radical addition to prochiral alkene. Herein, we realized a highly enantioselective radical hydroacylation of α-substituted α,β-unsaturated carbonyl compounds through direct hydrogen atom transfer in the presence of the photocatalyst anthraquinone and chiral N,N′-dioxide/metal complexes. This mild, robust method provided a facile access to a wide array of chiral ketones with α-tertiary stereocenters by using the readily available aldehyde as a hydroacylation reagent. Based on the spectroscopy experiments and control experiments together with DFT calculations, a hydrogen atom transfer/radical addition/enantioselective reverse hydrogen atom transfer sequence was proposed.