Reversal of Selectivity in Acetate Aldol Reactions of N-Acetyl-(S)-4-isopropyl-1-[(R)-1-phenylethyl]imidazolidin-2-one

Synergistic effects of the exo- and endocyclic chiral centers of an imidazolidinone-based auxiliary were investigated in the perspective of acetate aldol reactions. The reversal in diastereoselectivity was accomplished by lithium and titanium enolate reactions, which proceed through proposed open and closed transitions states, respectively. The aldol adducts were used in the stereoselective synthesis of fluoxetine.