Friedel-Crafts α-Aminoacylation of Aromatic Compounds with a Chiral N-Carboxy-α-amino Acid Anhydride (NCA); Part 2

Abstract

The N-carboxy-α-amino acid anhydrides (NCA) derived from L-Asp(OEt), L-Glu(OMe), L-Met, and L-Pro reacted with aromatic compounds (toluene or benzene) in the presence of AlCl3, to afford the corresponding α-aminoalkyl aryl ketones as hydrochloride salts in moderate yields. The β- and γ-amino acid esters, which were obtained from the reaction of the aromatic compounds with L-Asp(OEt)- and L-Glu(OMe)-NCA, were hydrolyzed by hydrochloric acid to the corresponding β- and γ-amino acids as hydrochloride salts. L-Phe-NCA did not react with benzene in the presence of AlCl3, instead an intramolecular acylation occurred to afford (S)-2-aminoindanone hydrochloride. The chiralities of the original L-α-amino acids were most retained during these α-aminoacylation.