Heterocyclic Synthesis with 3-Cyano-2(1H)pyridinethione: Synthesis of 3-Oxo-2,3-dihydroisothiazolopyridine and Related Compounds

Article abstract of DOI:10.1007/BF00808929

3-Carbethoxy-4,6-diphenyl-2-pyridine sulfonamide (5), can be cyclized to 3-oxo-2,3-dihydro-4,6-diphenylisothiazolo<5,4-b>pyridine-1,1-dioxide (2).Oxidation of pyridinethione 6 with Cl2/ H2O gave the sulfonyl chloride derivative 7, which can be ammonolyzed to 3-amino-4,6-diphenylisothiazolo<5,4-b>pyridine-1,1-dioxide (8), and 3-cyano-4,6-diphenylpyridine-2-sulfonamide (9).Hydrolysis of 6 gave 3-carboxamido-2(1H)pyridinethione (12) which can be oxidized with iodine to 3-oxo-4,6-diphenyl-2,3-dihydroisothiazolo<5,4-b>pyridine (13). 3-Methyl-4,6-diphenylisothiazolo<5,4-b>pyridine-1,1-dioxide (17) was also prepared from 6.