Reaction of 3-Chlorobenzo[d]isothiazole 1, 1-Dioxide with Sodium Alkyl Carbonates

Abstract

The reaction of 3-ch1 robqnzo[d]isothiazole 1, dioxide(5)with sodium alkyl c4rbon. ates (6) afforded N-alkoxycarbonylsaccharins(7), pseudosaccharin anhydride(8)and dialkyl pyrocarbonates (9). The proportions ef (7) and (8) in the products varied with the nature of alkyl groups in (6) the proportion of (7) decreased in the order of methyl ethyl ipropyl t-butyl, and that of (8) increased in the above erder. The mechanistic studies revealed that the reaction proceeded through 3-alkoxycarbonyloxybenz6[d]isothiazole 1, 1dioxide (10), which was produced in, itially by the reaction between (5) and (6). The pyrolysis of N-methoxycarbonylsaccharin (7a) gave N-methylsaccharin (13) and CO2, and that of Nethoxycarbonyl and N-isopropoxycarbbnylsaccharins (7 b and 7 c) yielded a mixture of saccharin (14), ethylene and CO2, and a mixture of (14), propylene and CO2., respectively.