Ionic liquid as an efficient promoting medium for fixation of carbon dioxide: a clean method for the synthesis of 5-methylene-1,3-oxazolidin-2-ones from propargylic alcohols, amines, and carbon dioxide catalyzed by Cu(I) under mild conditions.

[reaction: see text] The reactions of propargylic alcohols, aliphatic primary amines, and CO2 were conducted in CuCl/[BMIm]BF4 system to produce the corresponding 5-methylene-1,3-oxazolidin-2-ones under relatively mild conditions. The products could be conveniently isolated by means of liquid-liquid extraction. The solvent ionic liquid as well as CuCl catalyst can be recovered and reused three times without appreciable loss of activity. By this green approach, several new 5-methylene-1,3-oxazolidin-2-ones were prepared in excellent yields and purity and were well-characterized.