Vinylic addition polynorbornene as catalyst support: applications in organocatalysis and palladium-catalyzed c-c coupling reactions

Abstract

Vinylic addition polynorbornene can be used as a robust and inert support for different catalytic systems. Nitrogen Heterocyclic Carbenes, which can be attached to the polymer by an alkyl chain through one of the nitrogen atoms, have been used as recyclable organocatalysts in two different organic transformations with excellent results. These carbenes can also act as a ligand to form palladium complexes. Polymer-supported palladium complexes are active precatalysts in different carbon-carbon coupling reactions (Suzuki, Negishi). The polymer can be reused with small loss of activity. Polynorbornene can also bear diimine moieties useful in the synthesis of palladium complexes. These complexes have been tested in olefin polymerization and cross-coupling reactions. Additional studies reveal the relevance of the election of the solvent in some palladium catalyzed reactions. Some solvents like amides (DMF, NMP, DMA), diethers (Dioxane, DME) or ketones can induce the reduction of palladium-aryl complexes under certain conditions.