first example of near-room-temperature α-arylation of benzo[b]thiophenes is reported. The discovery rests on the observation of a switch in α-/β-regioselectivity at different loadings of Pd2(dba)3·CHCl3 in the coupling between benzo[b]thiophene and 4-iodotoluene. We show that this unprecedented regioselectivity switch is driven by a Ag(I)-mediated C–H activation at the α-C–H position, which becomes the
Selective Palladium-Catalysedipso Arylation of α,α-Disubstituted Benzo[b]thien-2-ylmethanols with Aryl Bromides using PCy3 as Ligand
作者:A. Beatrix Bíró、András Kotschy
DOI:10.1002/ejoc.200600929
日期:2007.3
α,α-Diphenylbenzo[b]thien-2-ylmethanol was treated with a series of arylbromides in the presence of palladium(II) acetate and tricyclohexylphosphane to give the appropriate 2-aryl-benzo[b]thiophenes in good to excellent yield with concomitant formation of benzophenone. The reaction wassuccessfully extended to α,α-diphenylbenzo[b]thien-3-ylmethanol, although in certain cases the transformation was