Diacetylene arenes

The transition metal-catalysed polycondensation of dibromoalkanes with diacetylene arenes in the presence of carbon dioxide, which leads to polyesters [scheme (17)], is an instance where the carbon-heteroatom bond is formed by coupling of the carboxylated species [5] ... 

Compound 3.921 was also used as a precursor to obtain diacetylenic sulfide 3.925. Heating the latter (benzene, 200°C, 1,4-cyclohexadiene, 4 hours) leads to a mixture of ethynyl-2-naphthylsulfide 3.926 and naphtho[2,l-t ]thiophene 3.927 with dominance of the first (Scheme 3.134) [411]. This shows that the intramolecular cyclization of arene radical with a triple bond can occur through intermolecular capture of hydrogen from 1,4-cyclohexadiene. 

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