Tricarbonyl(h6-arene)chromium(0) complexes as chiral auxiliaries: asymmetric synthesis of b-aminoesters and b- lactams by Reformatskii condensation

Highly stereoselective syntheses (e.e. >98%) of b-aminoesters I (Ar = Ph, 4-MeOC6H4; R1, R2 = H, Me) and b-lactams II were accomplished using enantiomerically pure tricarbonyl (h6benzaldimine)chromium complexes in a Reformatskii type reaction promoted by ultrasound. A correlation between the configuration of complexed imines and abs. configuration of b-lactam derivs. is reported.