Protic ionic liquid-catalyzed synthesis of oxazolidinones using cyclic carbonates as both CO2 surrogate and sustainable solvent.

Graphical abstract Highlights • The protic ionic liquid [HDBU][Im] was easily prepared from easily accessible materials. • [HDBU][Im] was developed as an efficient catalyst for carboxylative cyclization of the anilines with cyclic carbonate. • This protocol offers low catalyst loading, wide functionality tolerance and recycling of the catalyst. • This method can be regarded as indirect path to CO 2 fixation. • Bifunctional role of [HDBU][Im] is verified by NMR technique and DFT study. Abstract The thermodynamic stability and kinetic inertness represent substantial obstacles for direct chemical transformation of CO 2. Consequently, conversion of the CO 2 equivalent in an efficient and energy-saving manner has gained much attention being viewed as an indirect pathway to chemical utilization of CO 2. In this article, we would like to report the synthesis of oxazolidinones via the carboxylative cyclization of anilines with cyclic carbonate using protic ionic liquid 1,8-diazabicyclo[5.4.0]-7-undecenium imidazolide [HDBU][Im] as the bifunctional catalyst under mild conditions without addition of conventional organic solvents. The distinguished features of this protocol include low catalyst loading, wide functionality tolerance and convenient recycling of the catalyst. A series of functional groups such as Cl, Br, CH 3 , OCH 3 and NO 2 can be well tolerated under the reaction conditions, providing the corresponding products in moderate to good yields (61–92%). In addition, to shed light on the cooperative interactions of [HDBU][Im]/EC and [HDBU][Im]/aniline, NMR technique and DFT study were also performed, respectively. [ABSTRACT FROM AUTHOR]