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

Abstract

1-Bromo-2-phenylcyclopropene (2) underwent [2+2] dimerization to generate 1,2-dibromo-4,5-diphenyltricyclo[3.1.0.0(2,4)]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).

Nonlinear Polyfused Aromatics with Extended π-Conjugation from Phenanthrotriphenylene, Tetracene, and Pentacene: Syntheses, Crystal Packings, and Properties

“…The coupling reactions such as Suzuki coupling and Scholl reactions were carried out in a nitrogen atmosphere. 1,4-Dibromo-2,5-diphenylbenzene ( 3 ) and 1,2-dibromo-4,5-diphenylbenzene ( 7 ) were prepared according to known protocols. The purification of the compounds was carried out by column chromatography using silica gel with 60–230 mesh size as the stationary phase.…”

Stereo- and Regioselective 1,3-Dipolar Cycloaddition of the Stable Ninhydrin-Derived Azomethine Ylide to Cyclopropenes: Trapping of Unstable Cyclopropene Dipolarophiles

“…Cyclopropenes 1a , 1b , 1c , 1o , 1d , 1e , 1f , 1l , 1m , 1g – j , 1k , 1n , 2a , 2b , 2c , 2d , 2e , 2f , 2g – i , 3b , and 3c were prepared according to the literature data. Parent cyclopropene ( 3a ) was obtained according to a literature procedure with slight modifications .…”