Unexpeced Formation of Pyrrolo[2,1-b]thiazoles by Rearrangement of alpha-Hydroxydihydro-1,4-Thiazines

摘要

A new synthesis of pyrrolo[2,1-b]thiazoles (5) is described. Hydrolysis of acetoxy dihydro-1,4-thiazine (2) prepared by Pummerer reaction of dihydro-1,4-thiazine sulfoxide gave the intermediate alpha-hydroxy sulfide (4). Dehydration of 4 gave pyrolo[2,1-b]thiazoles (5). The reaction mechanism for the formation of 5 including the intermediate thiol (6) is discussed.