Mechanistic Studies on Bromocyclization of Unsaturated Thioester by Density Functional Theory and Experiment.

Abstract

Using sulfur-containing nucleophiles in halocyclization has been underexplored notwithstanding their potential to generate novel S-heterocycles and despite the extensive exploration of oxygen, nitrogen, and carbon nucleophiles. In this study, we focused on the bromocyclization of alkenoic thioesters with N-bromoacetamide, which leads to the formation of cyclic bromosulfides. Investigation into the mechanistic pathways of these reactions revealed that the sulfur atom behaves as a nucleophile, leading to S-acetylsulfonium intermediates. HBr and Br2 played significant roles in these transformations.