Ruthenium-Catalyzed Reduction of Carbon Dioxide to\nFormaldehyde

Abstract

Functionalization of CO₂ is a challenging goal and precedents\nexist for the generation of HCOOH, CO, CH₃OH, and CH₄ in mild conditions. In this series, CH₂O, a very\nreactive molecule, remains an elementary C₁ building block\nto be observed. Herein we report the direct observation of free formaldehyde\nfrom the borane reduction of CO₂ catalyzed by a polyhydride\nruthenium complex. Guided by mechanistic studies, we disclose the\nselective trapping of formaldehyde by in situ condensation with a\nprimary amine into the corresponding imine in very mild conditions.\nSubsequent hydrolysis into amine and a formalin solution demonstrates\nfor the first time that CO₂ can be used as a C₁ feedstock to produce formaldehyde.