Transfer Hydrogenation of Carbon Dioxide to Methanol Using a Molecular Ruthenium‐Phosphine Catalyst

Abstract

AbstractTransfer hydrogenation using molecular catalysts has become a powerful tool in synthetic chemistry and a wide range of unsaturated substrates can be reduced with this protocol. Whereas reactions using iso‐propanol as hydrogen donor are already well established, recent examples demonstrate the possibility to use linear alcohols from renewable resources. Herein, the first effective transfer hydrogenation of the challenging substrate carbon dioxide (CO2) directly to methanol is described, applying a molecular ruthenium catalyst and linear alcohols as the hydrogen source. In neat ethanol, TONs up to 121 are achieved under moderate pressures of CO2. Moreover, systematic investigations enable to propose initial acceptorless dehydrogenation of the alcohol, followed by the reduction of CO2 to methanol via ethyl formate, as mechanistic basis.