Microbial transformations of N-(4-chlorphenyl)-benzoisothiazolone

Summary The microbial degradation of N-(4-chlorphenyl)-benzoisothiazolone (1) was studied by Streptomyces species in analogy to the metabolism of this drug in animals. As main metabolite 2-thiomethyl-N-(4-chlorphenyl)-benzamide (3) was found. The corresponding sulfoxide (4) and the sulfone (5) were obtained as further transformation products. The unmethylated 2-sulfhydryl compound (2) could be isolated in only small amounts. The degradation pathway follows by these results via a reductive cleavage of the S-N-bond of the isothiazolone ring with subsequent methylation of the sulfhydryl group and further oxidation of the resulting thiomethyl substituent.