Ruthenium-Catalyzed Hydroformylation of Alkenes by using Carbon Dioxide as the Carbon Monoxide Source in the Presence of Ionic Liquids

The reaction of [BMI center dot Cl] (BMI = 1-butyl-3-methylimidazolium) or [BMMI center dot Cl] (BMMI = 3-butyl-1,2-dimethylimidazolium) with Ru-3(CO)(12) generates Ru-hydride-carbonyl-carbene species in situ that are efficient catalysts for a reverse water gas shift/hydroformylation/hydrogenation cascade reaction. The addition of H3PO4 increased the catalytic activity of the first step (i.e., the hydrogenation of CO2 to CO). Under the optimized reaction conditions [120 degrees C and 6.0 MPa CO2/H-2 (1:1) for 17 h], cyclohexene and 2,2-disubstituted alkenes were easily functionalized to alcohols through sequential hydroformylation/carbonyl reduction.