Synthesis and photochemistry of 2,2′-distyrylbiphenyl and 2,2′-bis-(4-phenylbuta-1,3-dienyl)biphenyl

2,2'-Distyrylbiphenyl and 2,2'-bis-(4-phenylbuta-1,3-dienyl) biphenyl have been prepared by Wittig reactions of 2,2'- bis(triphenylphosphoniomethyl)biphenyl dibromide with benzaldehyde and cinnamaldehyde, respectively, with sodium ethoxide as base. Their photolysis products have been shown by i.r., u.v., n.m.r., and mass spectra to be cyclobutane derivatives formed by intramolecular condensation.