Metal-free catalytic processes based on main-group elements have been demonstrated for a wide range of organic reactions, potentially enabling more sustainable and less toxic industrial processes. Frustrated Lewis Pairs (FLPs) are a particularly promising approach based on bulky Lewis acids and bases, whose steric crowding prevents the formation of a Lewis pair adduct. The unquenched Lewis basic and acidic centers are therefore able to interact cooperatively to activate substrates and thus catalyze reactions, including hydrogenations, hydrosilylations, and C-H activations among many others. However, the moisture-sensitivity and poor separability of typical small-molecule FLP catalysts hinder their applicability in comparison to established transition-metal catalysts.<br/>One avenue to recyclable metal-free catalysts is the incorporation of catalytically active species into polymers, which allows for the immobilization of the catalyst using resins or separation using solvent-solvent techniques. Recently, we developed a new approach based on Ring-Opening Metathesis Polymerization (ROMP) to generate bench-stable polymer-supported Lewis acids for FLP catalysis. In this presentation we will discuss our further explorations of this ROMP-borane system. This work provides a novel adaptation of FLP chemistry to polymers as catalysts that combine the advantages of homogeneous and heterogeneous catalysis.

ROMP-boranes: Polymer supported Lewis Acid catalysts

ACS Fall 2021

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