2-thioxo-1,3-dithioles also 1,3-dithiole

Both CSs and CSs were also successfully generated by the fragmentation of ionized 4,5-dioxo-2-thioxo-l,3-dithione (65) and 2-thioxo-l,3-dithiole (66) (90JA3750). Tire three sulfur atoms in the anion and cation radicals were chemically equivalent, suggesting that they take the D h (or C2u) form (67 or 68). On the other hand, under similar conditions, 3-thioxo-1,2-dithiole (69) yielded two isomeric cation radicals the (or 2 ) form and the carbon disulfide 5-sulfide form (70). Ab initio calculations on three electronic states of CS3 at the 6-31G -l-ZPVE level indicated that the C21, form (68) was more stable than the carbon disulfide 5-sulfide form (70) in the neutral (both singlet and triplet states) and the anion radical states, but 68 was less stable than 70 in the radical cation state. 

Bis[p-(bromomethyl)phenyl]-2,3-pyrazinedicarbonitrile gave 5,6-bis[p-(5-methylthio-2-thioxo-l,3-dithiol-4-ylthiomethyl)phenyl]-2,3-pyrazinedicarbonit-rile (255) [4-benzoylthio-5-methylthio-l,3-dithiole-2-thione, MeONa,MeOH, 40°C, until clear (debenzoylation) then substrate [, 40°C, 1 h 52%].1502 Also other examples.200,470,496 1248... 

Ethyl 5-phenyl-6-thioxo-1,2,3-dithiazine-3-carboxylate by boiling with 20% hydrochloric acid for 7 hours can be converted to ethyl (4-phenyl-5-thioxo-l,2-dithiol-3-yl)carbamate in 90% yield5 (see also reaction above). 

Studies by Mayer and his school have shown that replacement of the nitrogen group of enamines provides a synthetic method capable of considerable variation and especially useful for the preparation of sulfur heterocycles.486 For example, 3i/-l,2-dithiol-3-thiones are obtained by the action of hydrogen sulfide and sulfur on enamines, particularly in a polar solvent, at room temperature.487 If the sulfur is omitted, then at higher temperatures and in an apolar solvent 2JE7-thiopyrone-2-thiones are formed preferentially.488 Also, enamines can be cleaved to 1,1-dithiols by sulfur 489 enamines obtained from p-oxo carboxylic esters thus give 60-90% yields of / -thioxo carboxylic esters.490... 

ET-l,2-dithiole-3-thiones are also recent areas of interest with regard to cyclic dithioates. The chemistry of l,3-thiazoline-5-thiones (177 [108-110]),5-thioxo-... 

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