Supported Chiral Monodentate Ligands in Rhodium‐Catalysed Asymmetric Hydrogenation and Palladium‐Catalysed Asymmetric Allylic Alkylation

Abstract

A family of monodentate polystyrene-supported phosphites, phosphoramidites and phosphanes has been prepared and evaluated as ligands in rhodium-catalysed asymmetric hydrogenation and palladium-catalysed asymmetric allylic alkylation. The supported ligands yielded active and enantioselective catalysts, which in selected cases match the performance of the nonsupported counterparts. As expected, the performance of the supported ligands in the rhodium-catalysed hydrogenation depends on the nature of the ligand, the type of polymeric support, as well as on the substrate. Ad-

Palladium-Catalyzed Enantioselective Allylic Substitution

“…Kamer and co-workers obtained their best result with L134, with an ee of 58% in AAA (Fig. 45) [160]. ZhiDong and co-workers had a better ee of 64% in AAA with their ligand L135, using N-methyaminomethyl polystyrene resin [161].…”

The Synthesis of Chiral Phosphorus Ligands for use in Homogeneous Metal Catalysis

“…Kamer and co-workers supported several monodentate phosphorus ligands by reaction of hydroxylsubstituted polystyrene with phosphorus chlorides in the presence of a tertiary amine as base ( Figure 10). [123] The polymeric ligands were tested in the Rh-catalyzed asymmetric hydrogenation and Pdcatalyzed alkylation. Interestingly in comparison to non-supported parent ligands in several instances inferior enantioselectivities yielded, which confirm earlier observations by Doherty et al [124] However, a general correlation between supported and non-supported catalysts was not found.…”

Recent Applications of Polymer Supported Organometallic Catalysts in Organic Synthesis

“…Kamer and co-workers investigated the use of polymer-bound phosphoramidites, phosphites and related ligands in the asymmetric substitution of an allylic acetate using dimethylmalonate as the nucleophile, but found that although the conversion was high, the enantioselectivity was rather modest and not at the same level as seen for the solution phase counterparts [ 38 ]. Better results were obtained by Vidal-Ferran, Pericàs and colleagues who applied polymer bound diphenylphosphinooxazoline (PHOX) ligands in enantioselective amination of allylic acetates [ 39 ].…”