N-Tfa- and N-Fmoc-(alpha-aminoacyl)benzotriazoles as chiral C-acylating reagents under Friedel-Crafts reaction conditions.

Chiral N-Tfa- and N-Fmoc-protected (alpha-aminoacyl)benzotriazoles 1a-j undergo Friedel-Crafts-type reactions with indole, N-methylindole, pyrrole, N-methylpyrrole, and benzene in the presence of AlCl(3) in efficient two-step sequences leading to enantiomerically pure alpha-amino N-heterocyclic ketones 2, 3, 5, 6, and 7 or diketone 4. In the absence of a reactive partner, Phe- and Trp-derivatives 1a, 1d undergo intramolecular cyclization to afford 12 and 13, again with retention of chirality.