DBU-Promoted Demethoxylative Thioannulation of Alkynyl Oxime Ethers with Sulfur for the Synthesis of Bisisothiazole-4-yl Disulfides

An efficient synthesis of bisisothiazole-4-yl disulfides via the demethoxylative thioannulation of alkynyl oxime ethers with odorless elemental sulfur has been first developed. This transformation involves the N–O bond cleavage, the formation of multiple C–S and N–S bonds, providing an efficient way for constructions of both isothiazoles and disulfides. Straightforward elaboration of the products to isothiazole thioethers expands the synthetic utility of this reaction.