Enantioselective organocatalytic addition of azlactones to maleimides: a highly stereocontrolled entry to 2,2-disubstituted-2H-oxazol-5-ones.

The first highly diastereo- and enantioselective organocatalytic synthesis of 2,2-disubstituted-2H-oxazol-5-ones is described. The addition of oxazolones to maleimides is promoted by bifunctional thiourea catalysts, which afford the corresponding 2,2-disubstituted-2H-oxazol-5-ones with total regio- and stereocontrol.