Tuning the Reactivity of a Heterogeneous Catalyst using N-Heterocyclic Carbene Ligands for C-H Activation Reactions

International audience; Heterogeneous CatalysisTuning the Reactivity of a Heterogeneous Catalyst usingN-Heterocyclic Carbene Ligands for CH Activation ReactionsAlberto Palazzolo, TimothØe Naret, Marion Daniel-Bertrand, David-Alexandre Buisson,Simon Tricard, Philippe Lesot, Yannick Coppel, Bruno Chaudret, Sophie Feuillastre, andGrØgory Pieters*Abstract:We report the dramatic impact of the addition of N-heterocyclic carbenes (NHCs) on the reactivity and selectivityof heterogeneous Ru catalysts in the context of CH activationreactions. Using a simple and robust method, we prepareda series of new air-stable catalysts starting from commerciallyavailable Ru on carbon (Ru/C) and differently substitutedNHCs. Associated with CH deuteration processes, dependingon Ru/C-NHC ratios, the chemical outcome can be controlledto a large extent. Indeed, tuning the reactivity of the Ru catalystwith NHC enabled: 1) increased chemoselectivity and theregioselectivity for the deuteration of alcohols in organicmedia; 2) the synthesis of fragile pharmaceutically relevantdeuterated heterocycles (azine, purine) that are otherwisecompletely reduced using unmodified commercial catalysts;3) the discovery of a novel reactivity for such heterogeneous Rucatalysts, namely the selective C-1 deuteration of aldehydes