SELECTIVE ARYLATION OF A SI-H BOND IN O-BIS(DIMETHYLSILYL)BENZENE VIAC-H BOND ACTIVATION OF ARENES

Tris(dibenzylideneacetone)diplatinum catalyzed arylation of a Si-H bon d in o-bis(dimethylsilyl)benzene at 110-degrees-C via C-H bond activat ion of arenes to give o-(aryldimethylsilyl)-(dimethylsilyl) benzene in 81-87% yields. Chlorobenzene and anisole mainly gave the ortho isomer s, while the meta isomer was the major product in the reaction of tolu ene. The relative reactivity trends among arenes, as examined in compe titive experiments, were toluene < benzene < chlorobenzene < anisole. In the reaction of o-bis(deuteriodimethylsilyl)benzene with benzene, e xtensive H-D exchange took place between these two components, while t he deuterium label was not found in the phenylation product. H-D excha nge between the phenylation product and benzene-d6 did not occur eithe r. A mechanism involving PtSiMe2(o-C6H4)SiMe2 species via dihydrogen e limination followed by the reaction of the species with an arene molec ule was proposed.