Thiacyanocarbons. 5. Reactions of Tetracyano-1,4-dithiin and Tetracyanothiophene with Nucleophiles: Synthesis of Tetracyanopyrrole and Tetracyanocyclopentadiene Salts

Article abstract of DOI:10.1021/jo01313a019

Reactions at the double bonds of tetracyano-1,4-dithiin and tetracyanothiophene have been explored.Generally, nucleophiles attack the dithiin by an addition-elimination mechanism to produce divinyl sulfides.The resulting anions are stable, experience fragmentation, or undergo further condensation reactions to produce heterocyclic structures.For example, tetracyano-1,4-dithiin is converted by thiocyanate ion to a thiophenopyrimidine.In fragmentation reactions, the dithiin acts as a masked maleonitrile and as such is useful for the synthesis of tetracyanoethylene.Remarkably, the dithiin reacts with sodium azide to give tetracyanopyrrole and with reactive methyl compounds to give substituted tetracyanocyclopentadienide ions.Tetracyanothiophene reacts with nucleophiles in a manner similar to tetracyanodithiin but at higher temperatures.