Heterogeneous CeO2-catalyzed selective synthesis of cyclic carbamates from CO2 and aminoalcohols in acetonitrile solvent

Abstract

Highly selective synthesis of 2-oxazolidinone from CO2 and 2-aminoethanol in acetonitrile solvent was achieved over heterogeneous CeO2 catalyst. Yield of 2-oxazolidinone reached 97% at 97% 2-aminoethanol conversion with >99% 2-aminoethanol-based selectivity in the optimized reaction conditions. Various aminoalcohols were converted to the corresponding cyclic carbamates in high yields (82% to >99%) with high selectivity (91% to >99%). Complete retention of configuration for the aminoalcohols having a chiral center at the α-position of the hydroxyl group was also achieved. Kinetics and FTIR studies suggested the reaction mechanism over CeO2 that was composed of four steps: (1) formation of carbonate and carbamate adspecies of 2-aminoethanol on CeO2 from 2-aminoalcohol and CO2, (2) decomposition of the carbonate adspecies to the hydroxyl group and CO2, (3) nucleophilic addition of the hydroxyl group to the carbamate adspecies on CeO2, providing 2-oxazolidinone, and (4) desorption of 2-oxazolidinone and regeneration of CeO2.