Bromination of toluene and its meta- and para-substituted derivatives with NBS by irradiation using a tungsten lamp gave benzotribromides and cis- and trans-1,2-dibromo-1,2-diarylethylenes, while ortho-substituted toluenes gave benzal bromides. o-Xylene gave tetra- and pentabromides and m-xylene afforded a mixture of dibromodiarylethylenes.
Palladium(0) Complex-Catalyzed Debrominative Coupling of (Tribromomethyl)- and (Dibromomethyl)benzenes to Diarylacetylenes and 1,2-Diarylethenes
作者:Shuntaro Mataka、Guo-Bin Liu、Masashi Tashiro
DOI:10.1055/s-1995-3878
日期:1995.2
Palladium(0)-triphenylphosphine complex-catalyzed debrominative coupling reaction of (tribromomethyl)benzenes gave diarylacetylenes or a mixture of (E)- and (Z)-α,β-dibromostilbenes depending upon the substrate and the solvent being used. On the other hand, (dibromomethyl)benzenes afforded (E)-stilbenes selectively under the same reaction conditions.