Ce[N(SiMe3)2]3(THF)3-Catalyzed Hydroboration of CO2, Esters and Epoxides with Pinacolborane: Selective Synthesis of Methanol in Multigram Scale

Abstract

In this work, we have reduced CO2 with HBpin to afford borylated methanol product selectively in ~99% yield using Ce[N(SiMe3)2]3(THF)3 as a catalyst. This led to multigram scale isolation of methanol obtained from CO2 reduction via the hydrolysis of borylated methanol, this establishes the potential of Ce[N(SiMe3)2]3(THF)3 as an efficient homogeneous catalyst for the bulk scale methanol synthesis. A practical application of this catalytic system was also shown by reducing CO2-containing motorbike exhaust efficiently and selectively. Further, C‒O bond activation of esters and epoxides using HBpin and 1-2 mol% of Ce[N(SiMe3)2]3(THF)3 at 60 °C afforded the borylated alcohols in good to excellent yields, which can easily be hydrolysed to the eco-friendly corresponding alcohol. The stoichiometric experiments were performed to prove the formation of in-situ generated cerium hydride [Ce]-H as an active catalyst.

Keywords: Lanthanides, Cerium, Ester, Epoxide, CO2 Reduction, Hydroboration.