Platinum-Catalyzed Asymmetric Hydroformylation with a Polymer-Attached Optically Active Phosphine Ligand

Article abstract of DOI:10.1021/jo00372a017

A chiral ligand, analogous to 2,3-O-isopropylidene-2,3-dihydroxy-1,4-bis(dibenzophospholyl)butane (DBP-DIOP) (5), attached to linear and to cross-linked polymer supports was obtained either by copolymerization of (4R,5R)-2-(p-styryl)-4,5-bis<(tosyloxy)methyl>-1,3-dioxolane (2) with styrene (or with styrene and divinylbenzene) followed by phosphination with lithium dibenzophosphole or directly by copolymerization of (4R,5R)-2-(p-styryl)-4,5-bis<(dibenzophospholyl)methyl>-1,3-dioxalane (4) with styrene (or with styrene and divinylbenzene).Exchange of Pt(II) onto the polymers followed by addition of stannous chloride gave polymer-supported catalysts which were used for asymmetric hydroformylation of a variety of olefins.Hydroformylations utilizing the polymer-supported catalysts showed comparable rates and gave nearly the same optical yields as the homogeneous analogue 5.However, lower branched to normal ratios were obtained from the polymer-supported catalysts, especially with those which were cross-linked.The soluble polymer-supported catalyst could be recovered by precipitation with diethyl ether and filtration.Reuse of this catalyst showed no loss in rate or selectivity.Recycling of the cross-linked polymer was achieved by simple filtration with slight loss in rate but no loss in selectivity.