Co/Fe Dual Catalysis for Sequential Hydrosilylation-Isomerization:Access to Trisubstituted(E)-Alkenyl Silanes from Terminal Alkynes

By rational modification of electronic and steric properties of pincer ligands,a Co/Fe dual catalyst system is developed for one-pot sequential Markovnikov alkyne hydrosilylation and stereoselective alkene isomerization.The protocol provides an atom-economical and efficient approach to trisubstituted(E)-alkenyl silanes from widely accessible terminal alkynes with high regio-and stereoselectivities under mild conditions.The utility of this reaction was demonstrated by gram-scale synthesis and derivatization of bioactive molecules.The radical clock and trapping experiments indicated that radical pathway might be operative in the alkene isomerization step.