Dimethyl acetylene dicarboxylate electrophilic alkyne reactions

The reactions of electrophilic alkynes, such as DMAD (dimethyl acetylene-dicarboxylate), with metal per- and poly-chalcogenido complexes have been exploited for the synthesis of homoleptic and heteroleptic 1,2-dithiolene,... 

Reactions of alkynes with benzimidazole are also electrophilic processes. Thus, 1-vinyl-benzimidazole and 1,3-divinylbenzimidazolinone are formed by the addition of acetylene in aqueous dioxane at 160 and 200 °C to benzimidazole and benzimidazolinone, respectively. There is rather more complication involved in the reactions of such alkynes as dimethyl-acetylene dicarboxylate (DMAD) (see Section 4.07.1.8) with not only products of Af-alkylation, but also the formation of tricyclic products involved. 

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