Synthesis of 4-(4'-Chlorophenyl)-5-Phenyl-1,2-Dihydronaphthalene

Abstract

BF₃-catalysed cyclization reactions of 1-(biphenyl-2'-y1)- 1-(4″-chlorophenyl)but-3-en-1-ol yielded none of the desired title compound but only 9-(4'-chloropheny1)-10-ethylphenanthrene and 9-allyl-9-(4'-chlorophenyl) fluorene by alternative cyclization pathways. Corresponding cyclization of the related diene 1-(biphenyl-2'-yl)-1-(4″-chlorophenyl)buta-1,3-diene also failed to yield the desired title compound but gave instead the unexpected product 9-(4'-chlorophenyl) phenanthrene through a novel mechanism.

Flash pyrolysis of l-(biphenyl-2'-yl)-l-(4″-chlorophenyl)buta-1,3-diene gave the desired compound as a minor constituent of the reaction mixture, the major constituent being 4-(biphenyl-2'-yl)-7-chloro- 1,2-dihydronaphthalene.