Friedel-Crafts alpha-aminoacylation of aromatic compounds with a chiral N-carboxy-alpha-amino acid anhydride (NCA); Part 2

The N-carboxy-alpha-amino acid anhydrides (NCA) derived from L-Asp(OEt). L- Glu(OMe), L-Met, and L-Pro reacted with aromatic compounds (toluene or benz ene) in the presence of AlCl3 to afford the corresponding alpha-aminoalkyl aryl ketones as hydrochloride salts in moderate yields. The beta- and gamma -amino acid esters, which were obtained from the reaction of the aromatic c ompounds with L-Asp(OEt)- and L-Glu(OMe)-NCA, were hydrolyzed by hydrochlor ic acid to the corresponding beta- and gamma-amino acids as hydrochloride s alts. L-Phe-NCA did not react with benzene in the presence of AlCl3, instea d an intramolecular acylation occurred to afford (S)-2-aminoindanone hydroc hloride. The chiralities of the original L-a-amino acids were most retained during these alpha-aminoacylation.