Amino-acids and peptides. Part XVIII. Studies relating to the synthesis and conformation of a novel bicyclic peptide system

Abstract

The synthesis of a bicyclic system (I) derived by coupling the two fourteen-membered cyclic peptides cyclo-[L-(α-amino)-β-alanylglycyl-D-(α-tosylamino)-β-alanylglycyl](II) and cyclo-[D-β-aspartylglycyl-β-alanylglycyl](III), and related bicyclic compounds, is described. The conformations of the compounds are discussed in the light of evidence from ¹H n.m.r. spectroscopy and a crystal structure analysis of one of the monocyclic compounds.