New contributions to the chemistry of 2,2-bis(chlorothio)propanedioic diesters and diamides

The mechanism of the formation of gem-disulfenyl dichlorides 2 from active methylene compounds 1 and sulfur dichloride (via the chlorodithio derivativ es 12) has been elucidated. Reduction of 2 under a variety of conditions yi elds, in varying amounts, the corresponding 1,2,4,5-tetrathianes 14 with co ncomitant formation of the tetrasulfides 15 and/or the desulfurated disulfi dcs 16. The pyrolysis of 2 and of the corresponding bis(disulfides) 5 leads to 14, arguably via the corresponding thiosulfines 4. When compounds 2 are treated with cyanide ions, reduction takes place rather than substitution, leading to the corresponding 1,2,4-trithiolanes 19. The halogenation of 5 leads to mixtures of hexathiocanes 17, hexathiepanes 18, and tetrathiolanes 7 which, however, could not be obtained in pure form. The single-crystal s tructures of the key compounds 2a, 5ad, 5bd, and 16b have been determined b y X-ray diffraction.