Long-Range Intramolecular S → N Acyl Migration: A Study of the Formation of Native Peptide Analogues via 13-, 15-, and 16-Membered Cyclic Transition States

The intramolecular long-range S -> N acyl migration via 13-, 15-, and 16-membered cyclic transition states to form native tetra- and pentapeptide analogues was studied on S-acylcysteine peptides containing beta- or gamma-amino acids. The pH-dependency study of the acyl migration via a 15-membered cyclic transition state indicated that the reaction is favored at a pH range from 7.0 to 7.6. Experimental observations are supported by structural and computational investigations.