Bifunctional Iminophosphorane Superbases Enable the Highly Enantioselective Sulfa-Michael Addition to Fully Substituted Cyclopropene Carboxylic Acid Derivatives
Kang Yuan, Alberto I. Ristache, Szymon M. Kosc, Agamemnon E. Crumpton, Darren J. Dixon
Abstract
High Resolution Image Download MS PowerPoint Slide The metal-free catalytic enantioselective intermolecular conjugate addition of alkyl thiols to unactivated β-substituted cyclopropene carboxylic acid derivatives has been developed. High enantiomeric excesses and yields were consistently achieved across a broad range of thiol pronucleophiles and fully substituted cyclopropene electrophiles under mild reaction conditions, enabled by a novel tert -leucine-derived amide-containing bifunctional iminophosphorane (BIMP) catalyst. Additionally, lowering the catalyst loading to 5.0 mol % was possible and allowed the reaction to be carried out on a gram scale.
Topics & Concepts
ChemistryCyclopropeneBifunctionalEnantioselective synthesisElectrophileCarboxylic acidCatalysisOrganic chemistryAlkylEnantiomerAddition reactionOrganocatalysisConjugateIntermolecular forceReactivity (psychology)Medicinal chemistryBifunctional catalystCombinatorial chemistryCyclopropane Reaction MechanismsSynthetic Organic Chemistry MethodsSynthesis and Catalytic Reactions