Hydroformylation of Olefins with CO₂/H₂ and Hydrosilane by Copper/Cobalt Tandem Catalysis

A Cu/Co tandem catalysis protocol was developed to conduct the hydroformylation of olefins using CO₂/H₂ and PMHS (polymethylhydrosiloxane) as a readily available and environmentally friendly hydride source. This methodology was performed via a two-step approach consisting of the copper-catalyzed reduction of CO₂ by hydrosilane and subsequent cobalt-promoted hydroformylation with H₂ and the in situ formed CO. The optimized triphos oxide ligand, which presumably facilitates the migratory insertion of CO gives moderate to excellent yields for both terminal and internal alkenes. This earth-abundant metal catalysis provides a reliable and efficient way to afford useful aldehydes in industry using silicon by-product PMHS as hydrogen source and renewable CO₂ as carbonyl source.