The synthesis and conformational aspects of a novel dioxopiperazine—a possible β-turn constraint

A synthetic route to a novel α,α-diamino β-keto ethoxycarbonyl-containing dioxopiperazine, capable of mimicking a β-turn, is reported. The cis configuration of the dioxopiperazine has been rationalised by NMR spectroscopy, while computational energy calculations have been used to explain the reluctance to cyclise of N-terminal partially protected dipeptides containing α,α-amino groups.