Synthetic utilization of polynitroaromatic compounds. 2. Synthesis Of 4,6-dinitro-1,2-benzisothiazol-3-ones and 4,6-dinitro-1, 2-benzisothiazoles from 2-benzylthio-4,6-dinitrobenzamides

Cyclization of 2-benzylthio-4,6-dinitrobenzamides to 4,6-dinitro-1, 2-benzisothiazol-3-ones was achieved using SO(2)Cl(2) in CH(2)Cl(2) at room temperature. Alkylation of these heterocycles proceeded in a nonregioselective manner to yield a mixture of corresponding O- and N-alkylated products. Oxidation of 4,6-dinitro-1,2-benzisothiazoles (50% H(2)O(2) in AcOH) afforded the corresponding S-oxides and S, S-dioxides, depending on oxidation conditions. Unexpectedly, oxidation of a 3-methoxy derivative resulted in ring opening with the formation of the corresponding sulfamide. Chlorination of these 4,6-dinitro-1,2-benzisothiazol-3-ones (PCl(5)-POCl(3)) gave the expected 3-chloroisothiazoles.