Stereoselective Palladium‐Catalyzed C−F Bond Alkynylation of Tetrasubstituted <i>gem</i>‐Difluoroalkenes
Qiao Ma, Yanhui Wang, Gavin Chit Tsui
Abstract
Abstract A stereoselective Pd(PPh 3 ) 4 ‐catalyzed C−F bond alkynylation of tetrasubstituted gem ‐difluoroalkenes with terminal alkynes has been developed. This method gives access to a great variety of conjugated monofluoroenynes bearing a tetrasubstituted alkene moiety with well‐defined stereochemistry. Chelation‐assisted oxidative addition of Pd to the C−F bond is proposed to account for the high level of stereocontrol. An X‐ray crystal structure of a key monofluorovinyl Pd II intermediate has been obtained for the first time as evidence for the proposed mechanism.
Topics & Concepts
StereoselectivityChemistryAlkynylationPalladiumMoietyAlkeneCatalysisConjugated systemStereochemistryOxidative additionMedicinal chemistryCombinatorial chemistryOrganic chemistryPolymerFluorine in Organic ChemistryCatalytic C–H Functionalization MethodsCyclopropane Reaction Mechanisms