Study of Chemical Ligation Via 17-, 18- and 19-Membered Cyclic Transition States

Abstract

Unprotected S-acylated cysteine isopeptides containing α-, β- or γ-amino acid units have been synthesized, and their conversion to native hexapeptides by S- to the N-terminus ligations involving 17-, 18- and 19-membered cyclic transition states have been demonstrated both experimentally and computationally to be more favorable than intermolecular cross-ligations. A series of S-acyl peptides containing terminal cysteine residues has been synthesized and long-range acyl migration of these S-acyl peptides via 17-, 18- and 19-membered cyclic transition states has been studied. © 2012 John Wiley & Sons A/S.