MONO AND DIPHOSPHINE BORANE COMPLEXES GRAFTED ON POLYPYRROLE MATRIX -DIRECT USE AS SUPPORTED LIGANDS FOR RH AND PD CATALYSIS

A new versatile method for the synthesis of supported mono and diphosp hines on polypyrrole matrix is described, based on the protective bora ne complexation of the phosphorus atom. For the first time, the unknow n alkylation of a diphosphine ethano bridge, was obtained with near yi eld close to 70%, leading to its derivative 8 bearing the polymerizabl e pyrrole group on a side chain. The different supported mono and diph osphine boranes 12-15 have been applied with success in palladium-cata lyzed allylation, cross-coupling reaction and in rhodium-catalyzed hyd rogenation. It is of particular interest that supported phosphine bora nes can be used without previous decomplexation, forming in situ the c atalytically active species from Pd(OAc)(2) or RhCl3. Moreover, the re coverable polymer could be used again in rhodium-catalyzed hydrogenati on with a very good efficiency after several turn-overs. Nethertheless , we may point out that with palladium catalysis, the addition of Pd(d ba)(2) was necessary to recover the catalytic activity. These results demonstrate that the phosphine borane complexes are key precursors for the synthesis of functionalized mono and diphosphines, and for their direct use in generating catalysts. (C) 1998 Elsevier Science S.A. All rights reserved.