Condensation reactions of chloroformylsulphur chloride with 2- and 4-aminopyrimidines, 2-aminothiazole, and 2-amino-Δ2-thiazoline

Abstract

Treatment of 2- and 4-aminopyrimidines, 2-aminothiazole, and 2-amino-Δ²-thiazoline with chloroformylsulphur chloride in ethanol-free chloroform and in the presence of an organic base leads to the formation of 3,4-fused 1,2,4-thiadiazolones. Spectral evidence for the structure of the products is presented.

The structure of 5,6-dihydrothiazolo[2,3-c][1,2,4]thiadiazol-3-one (VII) has been confirmed by X-ray analysis. A mechanism is suggested for the acid catalysed desulphurisation of 5,7-dimethyl[1,2,4]thiadiazolo[4,3-c]-pyrimidin-3-one (IX) to give ethyl 2,6-dimethylpyrimidin-4-ylcarbamate.