Transition metal catalysed reactions using glass bead technology

Abstract

A successful method for rendering homogeneous transition metal catalysts heterogeneous has emerged from glass bead technology. The process generally combines high activity and selectivity with facile recyclability. Glass bead technology, and related approaches, have been applied to a wide range of reactions with results paralleling, and sometimes exceeding, those obtained from their homogeneous counterparts. Outlined is the current scope of this research, with an emphasis on work on supported palladium reagents. A novel approach for the retrieval of precious metals from reaction mixtures stemming from these studies is also outlined.

The Art of Meeting Palladium Specifications in Active Pharmaceutical Ingredients Produced by Pd‐Catalyzed Reactions

“…This approach has been taken by Williams and co-workers in a collaboration between the former Glaxo Wellcome R&D group and the Department of Chemistry at the University of Bath. [18] The original approach from these groups was to perform catalysis using transition metals supported on glass beads. This was quite successful, but in the interests of extending the utility of the glass beads, palladium removal was also attempted.…”

Polymer-Supported Carbene Complexes of Palladium: Well-Defined, Air-Stable, Recyclable Catalysts for the Heck Reaction

“…Other examples use nanostructured palladium clusters stabilized by propylene carbonate [21] or hydrophilic palladium complexes anchored in supported aqueous phases (glass-bead technology). [22] The N-heterocyclic dicarbene complexes 2 a and 2 b and their immobilized counterparts 3 a and 3 b are excellent catalysts for the arylation of olefins with aryl bromides. The catalytic activity of these materials was investigated in detail with activated, non-and deactivated aryl halides, and with styrene or n-butyl acrylate as the vinylic substrate (Tables 3 and 4).…”

Supported Fluorous Phase Catalysis on PTFE, Fluoroalkylated Micro‐ and Meso‐porous Silica

“…[1] The high catalyst mobility, low leaching levels and good reactivities offered by the SAPC approach have been exploited in a wide variety of catalytic reactions. [2][3][4][5][6] The concept has been extended to other combinations of immiscible solvents including supported organic phase catalysis, a mirror image of SAPC employing a supported hydrophobic solvent layer on reverse-phase silica and an immiscible polar bulk phase, [7] and supported ionic phase catalysis, where a silica surface, modified with imidazolium ions, supports [ 4 ]-containing rhodium catalysts for the hydroformylation of 1-hexene. [8] Fluorous chemistry, [9] exploiting the immiscibility of perfluorinated and organic solvents, offers alternative solvent combinations for supported catalysis that do not require water or highly polar ionic liquids.…”