Synthesis of 2H‐1,4‐thiazin‐3(4H)‐one 1‐oxide and 2H‐1,4‐thiazin‐3‐(4H)‐one 1,1‐dioxide, structural analogs of uracil

Abstract

The synthesis of 1,4‐thiazine 1‐oxide and 1,1‐dioxide analogs of the antibiotic emimycin is described. Reaction of methylthioglycolate with 1‐bromo‐2,2‐diethoxyethane gave methyl (2,2‐diethoxyethylthio)acetate (2). Treatment of 2 with methanolic ammonia followed by cyclization furnished 2H‐1,4‐thiazin‐3(4H)‐one (5). Oxidation of 5 with m‐chloroperoxybenzoic acid converted it to 2H‐1,4‐thiazin‐3(4H)‐one 1‐oxide (6). Oxidation of 2 with potassium permanganate, followed by treatment with methanolic ammonia, and cyclization gave 2H‐1,4‐thiazin‐3(4H)‐one 1,1‐dioxide.