Stereoselective Alkylation of Imines and its Application towards the Synthesis of β‐Lactams

(S)-4-Isopropyl-1-((R)-1-phenylethyl)imidazolidin-2-one was evaluated as a chiral auxiliary for asymmetric acetate and propionate Mannich-type reactions, by generation ofthe titanium enolates, affording excellent yields and stereoselectivities. The application of the auxiliary was exemplified in the stereoselective synthesis of ezetimibe.