Switchover of the diastereoselectivity induced by a simple selection of titanium(IV) halides in the addition reaction of silyl ketene acetals to a chiral imine

Article abstract of DOI:10.1016/00404-0399(50)0978L-

Switchover of the diastereoselectivity was recognized by a simple selection of titanium(IV) halides in the reaction of silyl ketene acetal with a chiral imine possessing a derivative of D-(-)-phenylglycine as an auxiliary. TiF₄ effected the formation of (3S)-β-amino ester, while TiCl₄ gave (3R)-isomer. The β-amino esters thus obtained were convened into the corresponding β-lactams on treatment with Me₃Al without loss of the stereochemical integrity.