title: A metal-ligand cooperative pathway for intermolecular oxa-Michael additions to unsaturated nitriles.
abstract: An unprecedented catalytic pathway for oxa-Michael addition reactions of alcohols to unsaturated nitriles has been revealed using a PNN pincer ruthenium catalyst with a dearomatized pyridine backbone. The isolation of a catalytically competent Ru-dieneamido complex from the reaction between the Ru catalyst and pentenenitrile in combination with DFT calculations supports a mechanism in which activation of the nitrile through metal-ligand cooperativity is a key step. The nitrile-derived Ru-N moiety is sufficiently Brønsted basic to activate the alcohol and initiate conjugate addition of the alkoxide to the α,β-unsaturated fragment. This reaction proceeds in a concerted manner and involves a six-membered transition state. These features allow the reaction to proceed at ambient temperature in the absence of external base.
authors: Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747 AG Groningen (The Netherlands).
authors: Sébastien
authors: S
authors: Perdriau
authors: Douwe S
authors: DS
authors: Zijlstra
authors: Hero J
authors: HJ
authors: Heeres
authors: Johannes G
authors: JG
authors: de Vries
authors: Edwin
authors: E
authors: Otten
mesh_terms: D008024:Ligands; D009570:Nitriles / Q000737:chemistry*; D012428:Ruthenium / Q000737:chemistry*
chemical_list: D008024:Ligands; D009570:Nitriles; D012428:Ruthenium
keywords: Michael addition; homogeneous catalysis; non-innocent ligands; pincer ligands; ruthenium