Solid phase synthesis of a diketopiperazine catalyst containing the unnatural amino acid (S)-norarginine

A cyclic dipeptide containing the unnatural amino acid (S)-norarginine, recently shown to display useful catalytic activity, has been synthesized in good yield and high chemical purity using a solid phase protocol. All reactions in the sequence, including a Hofmann rearrangement and cyclization to diketopiperazine, were performed on the Merrifield polystyrene resin and proceed in high yield. In addition to its improved yield, this new synthesis offers easy access to derivatives and a potential to employ combinatorial strategies to the search for novel catalytic cyclic dipeptides. Copyright (C) 1996 Elsevier Science Ltd