SELECTIVE SYNTHESES OF BIS[1,2]DITHIOLO[1,4]THIAZINES AND BIS[1,2]DITHIOLOPYRROLES FROM HUNIGS BASE

The reaction of N,N-diisopropylethylamine (Hunig's base) and disulfur dichloride in 1,2-dichloroethane, in the presence of DABCO, gives thio lo[5,4-b][4',5'-e][1,4]thiazinine-3,5-dithione (1), or, by addition of oxygen donors, the 3-oxo-5-thione 2 or 3,5-dione 3 derivatives are se lectively obtained. When the first reaction is performed in boiling ch lorobenzene, s[1,2]dithiolo[4,5-b][5',4'-d]pyrrole-3,5-dithione (4) is obtained by sulfur extrusion from 1, and in the presence of oxygen do nors, the 3-oxo-5-thione 5 or 3,5-dione 6 derivatives are selectively obtained. Some interconversions of compounds 1-6 are described, and a coherent set of reaction pathways for the formation of all six product s is proposed. X-ray diffraction shows that the new bis-dithiolothiazi ne ring system of 1-3 is folded out-of planarity about the thiazine N- S vector, with the N-ethyl group folded back over the thiazine ring in a scorpion-like conformation. The new bis-dithiolopyrrole ring system of 4-6 is planar and extensively delocalized.