Organocatalytic direct aldol and nitroaldol reactions between azetidine-2,3-diones and ketones or nitromethane

The reactions of enantiopure azetidine-2,3-diones with unmodified ketones or nitromethane were catalyzed by proline and N-methylephedrine, respectively, to give the corresponding 3-functionalized 3-hydroxy-β-lactams with good yields and total diastereoselectivities. It was observed that the use of both enantiomers of proline or of N-methylephedrine does result in identical levels of stereocontrol in the aldol and nitroaldol reactions.