Conformationally Restricted Cyclic Nonapeptides Derived from L-Cysteine and LL-3-Amino-2-piperidone-6-carboxylic Acid (LL-Acp), a Potent β-Turn Dipeptide Analogue

Article abstract of DOI:10.1021/jo00350a077

Syntheses of the cyclic nonapeptides cyclo-(Gly-L-Cys(Bzl)-Gly)3, cyclo(L-Pro-Gly-L-Cys(Meb))3, and cyclo-(L-Cys(Meb)-LL-Acp)3 are described, where Meb = p=methoxybenzyl and Acp = 3-amino-2-piperidone-6-carboxylic acid, a β-turn-inducing dipeptide analogue.Removal of the S-blocking groups from each is described, followed by ring-forming reaction with 1,3,5-tris(bromomethylene)benzene to form an unusual series of relatively rigid vase-shaped cage compounds.Strong binding of three water molecules to the Acp-derived cage is reported.