(S)-1-(tert-Butyl-dimethyl-silanyl)-4-phenyl-azetidine-2,3-dione

(3R,4S)-1-(tert-butyldimethylsilyl)-3-hydroxy-4-phenylazetidin-2-one

(3R,4S)-1-(tert-Butyl-dimethyl-silanyl)-3-(1-methoxy-1-methyl-ethoxy)-4-phenyl-azetidin-2-one