[4.2](2,2')(2,2')Biphenylophanetriyne: a twisted biphenylophane with a highly distorted diacetylene bridge

Org Lett. 2014 Apr 4;16(7):1940-3. doi: 10.1021/ol5004934. Epub 2014 Mar 14.

Abstract

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°. 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).