Hydrovinylation of Alkenes Catalyzed by the Ruthenium−Hydride Complex Formed in Situ from (PCy3)2(CO)RuHCl and HBF4·OEt2

A ruthenium−hydride complex, generated in situ from the reaction of (PCy 3 ) 2 (CO)RuHCl ( 1 ) with HBF 4 ·OEt 2, was found to be an effective catalyst for the hydrovinylation of alkenes. For example, the reaction of styrene with ethylene in the presence of 1 /HBF 4 ·OEt 2 (0.5 mol %) at room temperature produced the hydrovinylation product in 93% isolated yield. Both terminal alkenes and dienes were found to give the hydrovinylation products. Higher reaction temperature was required for the phenyl-substituted internal alkenes, in which cases the isomerized products were obtained.