α-Substitution effects on the ease of S → N-Acyl transfer in aminothioesters

Abstract

In S-acylcysteines and homocysteines, the efficacy and rate of S → N-acyl transfer (5 and 6 cyclic TSs) vary with the size of S-acyl group. Conformational and quantum chemical calculations indicate that the spatial distance, b(N-C), between the terminal amine and the thioester carbon is shortened by α-C(O)X (X=OH, OMe, NH2) substituents. Spatial distance, b(N-C), between the terminal amine and the thioester carbon is shortened by α-C(O)X (X=OH, OMe, NH2) substituents. © 2012 John Wiley & Sons A/S.