Nitroacetyl group as a peptide synthon: synthesis of dipeptides with an α,α-bisallylglycine residue at the N-terminus

Abstract

N-Nitroacetyl derivatives of L-proline, L-valine, and L-phenylalanine esters were prepared in two steps under mild conditions (Scheme 2). Regiospecific mono- and bis-allylation of these nitroacetyl derivatives were accomplished in presence of a Pd(0) catalyst. The bis-allyl derivatives 7-9 were obtained in 40-75% yield. The tertiary NO₂ group in these compounds could be transformed into an acetylamino group by Zn/AcOH/Ac₂O. The final products 11-13 are dipeptides in which the N-terminal glycine residue bears two α-allyl substituents.