Asymmetric Nazarov Cyclizations of Unactivated Dienones by Hydrogen‐Bond‐Donor/Lewis Acid Co–Catalyzed, Enantioselective Proton‐Transfer
Jan B. Metternich, Martin Reiterer, Eric N. Jacobsen
Abstract
We report an enantioselective Nazarov cyclization catalyzed by chiral hydrogen-bond-donors in concert with silyl Lewis acids. The developed transformation provides access to tri-substituted cyclopentenones in high levels of enantioselectivity (up to 95% e.e.) from a variety of simple unactivated dienones. Kinetic and mechanistic studies are consistent with a reversible 4π-electrocyclization C-C bond-forming step followed by rate- and enantio-determining proton-transfer as the mode of catalysis.
Topics & Concepts
ChemistryEnantioselective synthesisCatalysisLewis acids and basesHydrogen bondSilylationProtonChiral Lewis acidCombinatorial chemistryMedicinal chemistryOrganic chemistryStereochemistryMoleculePhysicsQuantum mechanicsAsymmetric Synthesis and CatalysisAxial and Atropisomeric Chirality SynthesisTraditional and Medicinal Uses of Annonaceae