Organocatalytic Enantioselective 1,6‐<i>aza</i>‐Michael Addition of Isoxazolin‐5‐ones to <i>p</i>‐Quinone Methides

Abstract

A thiourea‐Brønsted base bifunctional catalyst allowed the enantioselective 1,6‐ aza ‐Michael addition of isoxazolin‐5‐ones to p ‐quinone methides to give isoxazolin‐5‐ones having a chiral diarylmethyl moiety attached to the N atom with fair to good yields and enantiomeric excesses. To the best of our knowledge this reaction represents the first example of enantioselective N ‐alkylation of isoxazolin‐5‐ones as well as the first example of enantioselective 1,6‐ aza ‐Michael reaction involving p ‐quinone methides.