Enantioselective Conjugate Addition‐Protonation of 5H‐Oxazol‐4‐ones and 5‐Methylene 1,3‐Oxazolidine‐2,4‐diones: 2,2'‐Biphenol‐Induced Diastereoselectivity Switch

Abstract

Summary of main observation and conclusionA synthetic strategy for catalytic asymmetric conjugate addition‐protonation and diastereoselective switch between 5H‐oxazol‐4‐ones and 5‐methylene 1,3‐oxazolidine‐2,4‐diones was established. An array of chiral conjugate addition‐protonation products bearing 1,3‐O‐heterotertiary‐O‐heteroquarternary nonadjacent stereocenters were obtained in excellent yields, moderate to good diastereoselectivities, and excellent enantioselectivities (up to 97% yield, 11: 1 dr, and 98% ee). Induction by 2,2’‐biphenol could effectively promote the production of the corresponding diastereoisomers via cycloaddition intermedia.