Synthetic Routes to, Stabilities and Transformations of, and Characterization of (Carbamoyl)disulfanyl Chlorides and Related Compounds1,2

Previously unobserved (carbamoyl)disulfanyl chlorides were prepared by (i) addition of limiting aromatic secondary amine to (chlorocarbonyl)disulfanyl chloride; (ii) Harris reactions of sulfur dichloride with appropriate <i>O</i>-alkyl <i>N</i>-methyl-<i>N</i>-arylthiocarbamates; and (iii) regiospecific chlorolysis of bis(<i>N</i>-methyl-<i>N</i>-arylcarbamoyl)disulfanes. The newly synthesized unstable species were observed <i>in situ</i> by ¹H NMR and were trapped with alkenes, thiocarbamates, and thiols using methods precedented by the chemistry of analogous (carbamoyl)sulfenyl chlorides. Furthermore, each of the trapped products was synthesized by an alternate route, reinforcing conclusions about their structures. While (<i>N</i>-methyl-<i>N</i>-phenylcarbamoyl)disulfanyl chloride was unstable and decomposed quickly or cyclized intramolecularly, introduction of the <i>N</i>,2,6-trimethylphenyl moiety led to significantly improved stability. As part of this study, an interesting, unexpectedly stable 1,2,4-dithiazinone was discovered and its structure was established by X-ray crystallography. The new heterocycle, with its twisted out-of-plane disulfide bond in a six-membered ring, readily donated a sulfur atom to triphenylphosphine; this reaction resulted in the formation of triphenylphosphine sulfide, along with the corresponding highly stable heterocycle in which the single sulfur that remains is part of a planar five-membered ring, fused to a co-planar aryl moiety.