Synthesis of Biphenylenes and Their Higher Homologues by Cyclization of Aryne Derivatives.

This investigation demonstrates that a series of biphenylenes can be easily prepared from their corresponding halobiphenyls by the cyclization of in situ generated 2',3'-didehydro-2-lithiobiphenyls at low temperature. Two remarkable advantages of this synthetic method include 1) the lack of any need for transition-metal catalysts or reagents in the cyclization, and 2) the ability to obtain C1-functionalized products by treating the reaction intermediate 1-lithiobiphenylene with an electrophilic reagent. π-Extended derivatives, such as benzobiphenylenes, dibenzobiphenylene, linear/angular [3]phenylenes, and biphenyleno[2,3-b]biphenylenes, were synthesized similarly using suitable biaryls or teraryls.