Enantioselective Synthesis of Functionalized Diazaspirocycles from 4‐Benzylideneisoxazol‐5(4<i>H</i>)‐one Derivatives and Isocyanoacetate Esters
Pablo Martínez‐Pardo, Adrián Laviós, Amparo Sanz‐Marco, Carlos Vila, José R. Pedro, Gonzalo Blay
Abstract
Abstract Enantioenriched spirocyclic compounds bearing three contiguous stereocenters and high functionalization were obtained through a formal [3+2] cycloaddition reaction catalyzed by a cooperative system. The spiro compounds were synthesized from 4‐arylideneisoxazol‐5‐ones and isocyanoacetate esters using a bifunctional squaramide/Brønsted base organocatalyst derived from a Cinchona alkaloid and silver oxide as Lewis acid. This method afforded two out of the four possible diastereomers with good yields and high enantiomeric excess for both diastereomers. magnified image
Topics & Concepts
ChemistryEnantioselective synthesisStereocenterDiastereomerCinchonaEnantiomerCycloadditionCyclohexenoneBifunctionalOrganic chemistryOrganocatalysisSquaramideEnantiomeric excessLewis acids and basesStereochemistryCatalysisCombinatorial chemistryAsymmetric Synthesis and CatalysisCyclopropane Reaction MechanismsOxidative Organic Chemistry Reactions