Transition-Metal-Catalyzed Asymmetric Organic Synthesis via Polymer-Attached Optically Active Phosphine Ligands. 4. Asymmetric Hydroformylation

The suspension copolymerization of styrene, divinylbenzene, and 2-(p-styryl)-4, 5-bis[(tosyloxy)methyl]-1, 3-dioxolane (1) gave cross-linked beads containing a 10% incorporation of 1. Treatment of the copolymer with an excess of either sodium diphenylphosphide or the sodium salt of dibenzophosphole gave polymers containing the optically active 4, 5-bis[(diphenylphosphino)methyl]-l, 3-dioxolane (DIOP) (3) ligand or the corresponding dibenzophosphole (DIPHOL) derivative (4). Exchange of Rh(I)-carbonyl species onto the polymers gave polymer-attached catalysts for hydroformylation. The catalysts were characterized by ³¹P NMR T₁ studies and by electron-induced X-ray emission analysis. Hydroformylation of various olefins using the polymer-supported catalysts showed unique selectivities and equivalent optical yields when compared to that for homogeneous counterparts. The catalysts could be reused via simple filtration with no loss in rate or selectivity.