Chiral Phosphoric Acid‐Catalyzed Enantioselective Synthesis of Pyrazole‐Based Unnatural α‐Amino Acid Derivatives

Abstract

AbstractAn enantioselective synthesis of unnatural pyrazole‐based α‐chiral amino acid derivatives from the asymmetric reaction of N‐aryl‐5‐aminopyrazoles with β,γ‐alkynyl‐α‐imino esters using a chiral spirocyclic phosphoric acid catalyst was developed. Using the established methodology, various pyrazole‐based α‐amino acid derivatives with tetrasubstituted carbon stereocenters were obtained in 67–98% yields and with 73–99% enantioselectivities. The NH2 functionality in the corresponding products enables further transformations to a chiral thiourea and a lactam.magnified image