Synthesis and catalytic properties of diphosphinidenecyclobutene-coordinated palladium and platinum complexes

This account describes our recent studies on organopalladium and platinum complexes bearing 1,2-diaryl-3,4-diphosphinidenecyclobutenes (DPCB-Y). The DPCB-Y ligands bear extremely low-lying pi* orbitals mainly located around the sp(2)-hybridized phosphorus atoms and have a marked tendency to engage in metal to phosphorus pi-back-bonding. This property is useful for catalysis, leading to highly efficient organic transformations with hitherto unknown reactivities and selectivities. Detailed catalytic mechanisms are reported for dehydrogenative silylation of ketones and direct conversion of allylic alcohols into N- and C-allylation products. (C) 2004 Academie des sciences. Published by Elsevier SAS. All rights reserved.