Silicon-Based Lewis Acid Assisted Cinchona Alkaloid Catalysis: Highly Enantioselective Aza-Michael Reaction under Solvent-Free Conditions
作者:Hua-Meng Yang、Li Li、Fei Li、Ke-Zhi Jiang、Jun-Yan Shang、Guo-Qiao Lai、Li-Wen Xu
DOI:10.1021/ol202803b
日期:2011.12.16
The study showed that a combination of an achiral silicon-based Lewis acid and chiral Lewis base, such as iodotrimethylsilane (TMSI) and cinchonine, generated a highly enantioselective catalyst system under solvent-free conditions which gave aromatic beta-amino ketones with up to >99% ee. Mechanistic studies demonstrate the enhanced asymmetric induction may be due to the combined and competitive activation of a carbonyl moiety of chalcone with cinchonine and the silicon-based Lewis acid in the aza-Michael reaction.