Enantioselective Syntheses of 3,4‐Dihydropyrans Employing Isochalcogenourea‐Catalyzed Formal (4+2)‐Cycloadditions of Allenoates
Magdalena Piringer, Mario Hofer, Lukas S. Vogl, Péter Mayer, Mario Waser
Abstract
We herein successfully demonstrate the use of chiral isochalcogenoureas as Lewis Base catalysts for a variety of (4+2)-cycloaddition reactions of allenoates and different Michael acceptors. In all cases the same structural key-motive, a dihydropyran with a (Z)-configurated exocyclic double bond could be accessed as the major regio- and diastereoisomer in an enantioselective manner. Furthermore, these chiral dihydropyrans were successfully engaged in different follow-up transformations.
Topics & Concepts
Enantioselective synthesisChemistryCatalysisOrganocatalysisCombinatorial chemistryOrganic chemistryAsymmetric Synthesis and CatalysisSynthetic Organic Chemistry MethodsCatalytic Alkyne Reactions