The Crossed [2+2] Cycloaddition of 1-Phenylcyclopropene and 1-Bromo-2-phenylcyclopropene

1-Bromo-2-phenylcyclopropene (2) underwent [2+2] dimerization to generate 1,2-dibromo-4,5-diphenyltricyclo[3.1.0.02,4]hexane (5), which was heated to form 1,2-dibromo-4,5-diphenylcyclohexa-1,4-diene (6) followed by oxidation to yield 4′,5′-dibromo-o-terphenyl (7). o-Terphenyl 7 could be synthesized in one-pot reactions from 1,1,2-tribromocyclopropane (3). When cyclopropane 3 was treated with 1.5 equiv of methyllithium followed by slowly adding the proton source, crossed [2+2] adduct 8 was isolated in 40% yield. Compound 8 was heated and oxidated to produce 4′-bromo-o-terphenyl (11).

1-溴-2-苯基环丙烯（2）经过[2+2]加成二聚反应生成了1,2-二溴-4,5-二苯基三环[3.1.0.02,4]己烷（5），随后加热该化合物以形成1,2-二溴-4,5-二苯基环己烯-1,4-二烯（6），并进一步氧化得到4',5'-二溴-o-三苯基（7）。o-三苯基7可以通过一锅反应从1,1,2-三溴环丙烷（3）合成。当环丙烷3与1.5等当量的甲基锂反应后，缓慢加入质子源，可得到40%产率的交叉[2+2]加成物8。化合物8经加热和氧化后，生成了4'-溴-o-三苯基（11）。