Organocatalyzed Enantioselective Decarboxylative Mannich Reaction of β‐Ketoacids with Pyrazolinone Ketimines for the Construction of Chiral β‐Amino Ketone‐Pyrazolinone Derivatives

Abstract

An organocatalytic enantioselective decarboxylative Mannich reaction of pyrazolin‐5‐one derived ketimines with β‐ketoacids using quinine‐derived bifunctional squaramide as a catalyst has been developed. With the developed protocol, a series of chiral β‐amino ketone‐pyrazolinone derivatives were obtained in excellent yields (up to 99 %) with good enantioselectivities (up to 94:6 er). The enantioselective decarboxylative aldol reaction of pyrazole‐4,5‐dione with β‐ketoacids was also realized under the standard reaction conditions.