The O2-./ CO2 system as mild and safe carboxylating reagent. Synthesis of organic carbonates

The O2-./ CO2 system, originating from electrochemical one-electron reduction of dioxygen in dipolar aprotic solvents and in the presence of CO2, converts primary and secondary alcohols bearing a leaving group at α orβ position into the corresponding cyclic carbonates in high to excellent yields. Unsubstituted alcohols are also converted, but in unsatisfactory yields, into the corresponding alkyl ethyl carbonates after completion of the reaction by addition of Etl. Tertiary alcohols and phenols are stable to the reagent, thus allowing selective carboxylation of polyhydroxy derivatives. CH-acid containing compounds underfo diferent reactions, if any, with the reagent but in the cases under study the formation of carboxylation products has never been observed.