Microwave‐Assisted Synthesis of β ‐Lactams and Cyclo‐ β ‐dipeptides

Different cyclo‐ β ‐dipeptides were prepared from corresponding N ‐substituted β ‐alanine derivatives under mild conditions using PhPOCl 2 as activating agent in benzene and Et 3 N as base. To evaluate β 3 ‐substituent influence, the amino acids 7 – 26 were synthesized, and a β ‐lactam formation reaction was carried out instead of cyclo‐ β ‐dipeptide formation. The crystal structures of three derivatives of cyclo‐ β ‐peptides and one β ‐lactam are presented.