1.3- Dithiole-2-thione, chlorination

Dichloro-l,2-dithiole-3-thione (1) undergoes 1,3-cycloaddition with DMAD to give the adduct (2).1 On further heating with alkynes, regiospecific cycloaddition and molecular rearrangement occur with loss of chlorine to give 7//-thieno[2,3-c]thiopyran-7-thiones (3) and 4//-thieno[3,2-c]thiopyran-4-thiones (4). 

Dithiole-2-thione (176) reacts with (V,A/-dichIorosulfonamides to give the 1,3-dithiol-2-ylidenesulfonamides (177) and (178) as well as the 1,3-dithiole-2-thione oxide (179). It has been established that the primary step in these reactions is nucleophilic attack of the exocyclic sulfur of the l,3-dithiole-2-thione on the chlorine of the amide to produce an ion pair which can react in three ways to furnish the l,3-dithiol-2-ylidenesulfonamides (79LA689). 

Chlorine in hot acetic acid gives very poor yields (0-5%) of 3-(p-methoxy-phenyl)-l,2-dithiolium hydrogen sulfate from 5-(p-methoxyphenyl)-l,2-dithiole-3-thione. ... 

Chlorinated products obtained from l,2-dithiole-3-thiones and chlorine have been ascribed dichloride structure 65, but have been shown to be isomeric salts 66.116... 

S-Isopropyl and N-isopropyl groups are converted to 3H-l,2-dithiole-3-thione rings by sulfuration and chlorination with disulfur dichloride [82,83]. 

The condensation of aldehydes with thiocyanoacetic esters, catalysed by potassium fluoride or potassium carbonate, gave as minor products yV-carbamoyl-2-imino-5-alkyl(or aryl)-l, 3-oxathiolan-4-carboxylic esters, in which the 4,5-c/j-isomers predominated according to n.m.r. spectroscopy. l,3-Oxathiolan-2-thione was converted into dimethyl 1,3-dithiol-2-one-4,5-dicarboxylate and ethylene on treatment with dimethyl acetylene-dicarboxylate, and the transformation of methyl 2-methoxycarbonyl-methyl-1,3-oxathiolan-2-carboxylate into dimethyl-5,6-dihydro-l, 4-oxa-thiin-2,3-dicarboxylate by chlorination at low temperatures found analogy in the reactions of 2,2-dialkyl-l,3-oxathiolans. Thiomethoxymethyl hexachloroantimonate reacted with potassium t-butoxide to give mainly 3,5,5-trimethyl-l,3-oxathiolanium hexachloroantimonate the mechanism of this remarkable reaction was not settled. ... 

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