Cycloaddition in Synthesis of Sulfonamide Derivatives. IV. One-Pot Synthesis of 3-Dimethylamino-4,1,2-benzoxathiazine 1,1-Dioxides, 3-Methoxy-4-methyl-1,2,4-benzothiadiazine 1,1-Dioxide and 3-Dimethylamino-1,4,2-benzodithiazine 1,1-Dioxides.

Abstract

A novel, one-pot synthesis of 3-dimethylamino-4, 1, 2-benzoxathiazine 1, 1-dioxides (7), 3-methoxy-4-methyl-1, 2, 4-benzothiadiazine 1, 1-dioxide (9) and 3-dimethylamino-1, 4, 2-benzodithiazine 1, 1-dioxides (11) is described. The procedure in the case of 7 involves [2+2] cycloaddition reaction of chlorosulfonyl isocyanate (CSI) with thiocarbamates with subsequent loss of carbonyl sulfide, followed by cyclization of the resulting N-chlorosulfonyl isothioureas under Friedel-Crafts conditions. Synthesis of 9 was achieved similarly. Also, by using dithiocarbamates instead of thiocarbamates, the 1, 4, 2-benzodithiazines 11 were synthesized.