Ruthenium-Catalyzed Coupling Reactions of CO2 with C2H4 and Hydrosilanes towards Silyl Esters

A series of in situ-prepared catalytic systems incorporating Ru-II precursors and bidentate phosphine ligands has been probed in the reductive carboxylation of ethylene in the presence of triethylsilane as reductant. The catalytic production of propionate and acrylate silyl esters was evidenced by high-throughput screening (HTS) and implemented in batch reactor techniques. The most promising catalyst systems identified were made of Ru(H)(Cl)(CO)(PPh3)(3) and 1,4-bis(dicyclohexylphosphino)butane (DCPB) or 1,1'-ferrocene-diyl-bis(cyclohexylphosphine) (DCPF). A marked influence of water on the acrylate/propionate selectivity was noted. Turnover numbers [mol mol(Ru)(-1)] up to 16 for acrylate and up to 68 for propionate were reached under relatively mild conditions (20 bar, 100 degrees C, 0.5 mol % Ru, 40 mol % H2O vs. HSiEt3). Possible mechanisms are discussed.

Automated summary

This study investigated the catalytic systems incorporating Ru-II precursors and bidentate phosphine ligands in the reductive carboxylation of ethylene, identifying promising catalyst systems and noting a significant influence of water on product selectivity. High turnover numbers for acrylate and propionate were achieved under relatively mild conditions, and possible mechanisms are discussed.