Studies on heterocyclic chemistry. Part 24. Syntheses of the 4-arylisothiazol-3-yl O-thioesters utilising the S-thioester →O-thioester rearrangements of the 4-aryl-5-thioxo-3-isothiazolin-3-yl S-thioesters induced by acylation reagents, peracid, or N-bromosuccinimide
Abstract
A number of 4-arylisothiazol-3-yl O-thioesters have been prepared utilising the S-thioester →O-thioester rearrangements of the 4-aryl-5-thioxo-3-isothiazolin-3-yl S-thioesters (1). Reactions of the isothiazolines with acylation reagents (e.g. acyl chloride or acid anhydride) in the presence of boron trifluoride afforded the 5-acylthio-4-arylisothiazol-3-yl O-thioesters (2), which were also prepared by the reactions of the thallium(I) 4-aryl-5-sulphidoisothiazol-3-yl O-thioesters (3) with acyl chloride. Reactions of the isothiazolines with m-chloroperbenzoic acid gave the 5,5′-dithiobis(4-arylisothiazol-3-yl O-thioesters)(5) and the 4-arylisothiazol-3-yl O-thioesters (6). The disulphides (5) were also accessible by the reaction of the isothiazolines with N-bromosuccinimide.