Efficient Fluoride-Catalyzed Conversion of CO_2 to CO at Room Temperature

摘要

A protocol for the efficient and selective reduction of carbon dioxide to carbon monoxide has been developed. Remarkably, this oxygen abstraction step can be performed with only the presence of catalytic cesium fluoride and a stoichiometric amount of a disilane in DMSO at room temperature. Rapid reduction of CO_2 to CO could be achieved in only 2 h, which was observed by pressure measurements. To quantify the amount of CO produced, the reduction was coupled to an aminocarbonylation reaction using the two-chamber system, COware. The reduction was not limited to a specific disilane, since (Ph_2MeSi)_2 as well as (PhMe_2Si)_2 and (Me_3Si)_3SiH exhibited similar reactivity. Moreover, at a slightly elevated temperature, other fluoride salts were able to efficiently catalyze the CO_2 to CO reduction. Employing a nonhygroscopic fluoride source, KHF_2, omitted the need for an inert atmosphere. Substituting the disilane with silylborane, (pinacolato)BSiMe_2Ph, maintained the high activity of the system, whereas the structurally related bis(pinacolato)diboron could not be activated with this fluoride methodology. Furthermore, this chemistry could be adapted to ~(13)C-isotope labeling of six pharmaceutically relevant compounds starting from Ba~(13)CO_3 in a newly developed three-chamber system.