2-Arylidene-3,4-dihydro-4-hydroxy-3-oxo-2H-1,4-benzothiazine hydroxamic acids (VI) were best prepared by the reduction of α-(o-nitrophenylthio)cinnamates and related compounds of general structure V with sodium borohydride and palladium–charcoal. These precursors (V) were obtained by reacting methyl (o-nitrophenylthio)acetate and its simple derivatives with a variety of aryl aldehydes, in the presence of piperidine. Attempts to prepare the sulfones of V in a similar manner from methyl or ethyl (o-nitrobenzenesulfonyl)acetate were successful in two instances when absolute methanol or ethanol was the solvent. The alternative reaction, in which one molecule of the aldehyde condensed with two molecules of the (o-nitrobenzenesulfonyl)acetate, also occurred.Methyl and ethyl (2-nitrobenzenesulfonyl)acetate and their simple ring-substituted derivatives were smoothly hydrolyzed and decarboxylated by heating a solution of the acetate in aqueous alcohol containing piperidine. Methyl p-nitrophenylsulfone is similarly obtained in an excellent yield from methyl (p-nitrobenzenesulfonyl)acetate. Neither methyl (o-nitrophenylthio) acetate nor methyl α-(4-trifluoromethyl-2-nitrobenzenesulfonyl)propionate is affected by this treatment.
Antifungal Activity of Isothiocyanates and Related Compounds
