Highly Efficient Ruthenium‐Catalyzed Semi‐hydrogenation of Urea Derivatives to Formamides.

The utilization of CO2 as a non‐toxic and cheap feedstock for C1 is a desirable route to achieve high value‐added chemicals. In this context, we report a highly efficient ruthenium‐catalyzed semi‐hydrogenation reaction of CO2‐derived ureas. Various alkyl and aryl urea derivatives were successfully hydrogenated to obtain the corresponding recyclable amines and formamides (up to 97 % yield), highlighting the good substrate applicability of this method, which makes this method a sustainable alternative for the hydrogenation of CO2 to formamides in the presence of amines. In the meantime, we have discovered a new pathway that enables rapid hydrogenation of urea derivatives even at lower H2 pressure (<5 bar). This methodology might provide a new insight into the reduction functionalization of CO2 under mild pressure to form new C−N bond. Based on the control experiments and the observed intermediate products, we clarify the mechanism for selective semi‐hydrogenation of ureas. [ABSTRACT FROM AUTHOR]