Platinum-catalyzed asymmetric hydroformylation with a polymer-attached optically active phosphine ligand

Abstract

A chiral ligand, analogous to 2,3-0-isopropylidene-2,3-dihydroxy-l,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]-l,3-dioxolane (2) with styrene (or with styrene and divinylbenzene) followed by phosphination with lithium dibenzophosphole or directly by copolymerization of (4R,5R)-2-{pstyryl)-4,5-bis[(dibenzophospholyl)methyl]-l,3-dioxalane (4) with styrene (or with styrene and divinylbenzene).Exchange of Pt(II) onto the polymers followed by the addition of stannous chloride gave polymer-supported catalysts which were used for asymmetric hydroformylation of a variety of olefins. Hydroforymlations 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.

The asymmetric hydroformylation in the synthesis of pharmaceuticals

“…Use of the [(-IDIPHOLlF't(SnC1,)Cl catalyst allowed a faster reaction with a higher ee (70%), but low aldehyde selectivity was obtained (57%) (Scheme 4). 27 The hydroformylation of N-vinylphthalimide in the presence of [( -1-BPPMI PtCl2/SnCl2 gave a 52% conversion and 85% chemoselectivity, but the regioselectivity was not in favor of the useful branched aldehyde…”

Aspects of Immobilisation of Catalysts on Polymeric Supports

“…[44] PS-supported DIOP [ = 2,3-O-isopropylidene-2,3-dihydroxy-1,4-bis(diphenylphosphino)butane] was the first immobilised asymmetric bidentate phosphine (Scheme 12). [52,53] Upon hydrogenation of prochiral substrates identical chemical and enantioselectivities was observed with the homogeneous and with the immobilised Rh-DIOP catalyst.…”

Alternative Metalle für die homogen katalysierte Hydroformylierung

“…Es ist jedoch zu beachten, dass dieser Austausch des Lçsungsmittels in einer Verminderung der Katalysatoraktivität resultierte. [106] Die guten Ergebnisse beim Einsatz eines wohldefinierten, von 4-Hydroxy-l-prolin abgeleiteten Platin-Diphosphin-Komplexes konnten auf eine Vielzahl von Vinylarenen übertragen werden. [107] [101] Schema 36.…”