Fast Addition of s-Block Organometallic Reagents to CO2 -Derived Cyclic Carbonates at Room Temperature, Under Air, and in 2-Methyltetrahydrofuran

Abstract

Fast addition of highly polar organometallic reagents (RMgX/RLi) to cyclic carbonates (derived from CO₂ as a sustainable C1 synthon) has been studied in 2-methyltetrahydrofuran as a green reaction medium or in the absence of external volatile organic solvents, at room temperature, and in the presence of air/moisture. These reaction conditions are generally forbidden with these highly reactive main-group organometallic compounds. The correct stoichiometry and nature of the polar organometallic alkylating or arylating reagent allows straightforward synthesis of: highly substituted tertiary alcohols, β-hydroxy esters, or symmetric ketones, working always under air and at room temperature. Finally, an unprecedented one-pot/two-step hybrid protocol is developed through combination of an Al-catalyzed cycloaddition of CO₂ and propylene oxide with the concomitant fast addition of RLi reagents to the in situ and transiently formed cyclic carbonate, thus allowing indirect conversion of CO₂ into the desired highly substituted tertiary alcohols without need for isolation or purification of any reaction intermediates.

Keywords: CO2; Grignard reagents; cyclic carbonates; green chemistry; organolithium compounds.