Synthesis of dipeptides containing propargylglycine and 2‐aminopimelic acid

Two dipeptides containing antibacterial amino acids, 2-aminopimelic acid (Apm) and propargylglycine (Pra), were synthesized: L-Pra-ambo-Apm (1) and ambo-Apm-L-Pra (2). 1 was easily obtained from the protected derivative resulting from the coupling (carbodiimide method) of Boc-L-Pra-OH with H-ambo-Apm(OBu1)-OBu1. For 2, we followed a synthesis scheme in which the e-carboxyl group of Apm was unprotected: after the coupling of Boc-rac-Apm-N3 with H-L-Pra-OBu1, mild acidolytic treatment afforded the desired dipeptide. 2 displayed weak antibacterial activity against some species.