Benzimidazolin-2-thione, alkylation

Benzimidazoline, 2,2-bis(trifluoromethyl)-synthesis, 5, 471 Benzimidazolines acidity, 5, 425 Benzimidazolinethiones Mannich reaction, 5, 390 synthesis, 5, 460 Benzimidazoline-2-thiones alkylation, 5, 444—445 S-alkylation, 5, 444 mercuration, 5, 445 reactions... 

When benzimidazoline-2-thiones are treated with the mercury salt of phenylacetylene the products are mercury(II) benzimidazole-2-thiolates (237), which form the disulfides when treated sequentially with sodium iodide and iodine. Such thiolates can be benzoylated on nitrogen by benzoyl chloride (Scheme 131) (77LA106). While the acylation of thiones in general can take place, like alkylation, either on nitrogen or sulfur (or both), there is a preference in favour of iV-acylation. 

In 1999, the first annulated carbene derived from benzimidazole, l,3-bis(2,2-dimethylpropyl)benzimidazolin-2-ylidene, was prepared by the reduction of A/,N -dialk ylated benzimidazol-2-thione with Na/K in toluene [44]. Frequently, benzimidazolium ions containing less bulky Af-alkyl groups interconvert rapidly into enetetramine derivatives. Even when the formation of these compounds can be avoided by sterically demanding substituents, the final generation of the carbene may fail. 

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