On the Necessity of One‐Pot Tautomer Trapping in Asymmetric Michael Reactions of Arylideneisoxazol‐5‐ones

Herein we report the first asymmetric Michael reaction of arylidene‐isoxazol‐5‐one with 1,3‐diesters. Despite complex tautomer equilibria of the obtained Michael adducts, the one‐pot entrapping strategy by the aid of different electrophiles/protecting groups led to the selective isolation of diverse N‐substituted isoxazol‐5‐ones in very high overall yield and good enantioselectivity. Asymmetric three components Michael/electrophilic tautomer‐entrapping and four‐component Knoevenagel/Michael/electrophilic‐tautomer‐entrapping methodologies have also been developed. The enantiopurity of several final products was further increased after crystallization, up to > 99.9:0.1 er in good overall yields.