Benzobarrelene substituted

Benzyne and substituted benzynes, generated by thermal decomposition of 2-carboxybenzenediazonium chloride or by aprotic diazotization of appropriate anthranic acids, reacted with a variety of thiophene dioxides to produce naphthalene derivatives generally in moderate yields (Scheme 56) [34,159]. In two cases, the naphthalenes so produced further reacted with benzyne to give benzobarrelene derivatives. 

A further issue of regiocontrol emerges when three distinct n-systems are attached to a common sp -hybridized carbon. Such a situation is encountered not only in substrate 56 but also in cases like the cyano-substituted benzobarrelene 74 which upon direct irradiation rearranges, via intermediate 75, to give semibullvalene 76 (8%) as the only observable product of a DPM rearrangement reaction.Compound 75 is the more stable of the two possible 1,3-diradicals... 

In the example at the top of the slide, the monomers were hexyl- and undecyl-substituted benzobarrelenes and these side-chain-substituted systems are soluble and undergo... 

---