[4.2](2,2′)(2,2′)Biphenylophanetriyne: A Twisted Biphenylophane with a Highly Distorted Diacetylene Bridge

Biphenylophane 1 bridged by acetylene and diacetylene linkages was synthesized. X-ray analysis revealed its highly deformed diacetylene unit with a bond angle of 160 degrees. Enantiomers of 1 resolved by chiral HPLC underwent facile racemization with an activation energy of 90.6 kJ mol(-1). Transannular cyclization of 1 was induced by heating to generate benzyne intermediate 8, which was intercepted by furan to give 9, and by treatment with bromine to give dibromodibenzopicene (10).