(S)-3-Benzyl-4-((S)-2,2-dimethyl-[1,3]dioxolan-4-yl)-oxazolidine-2,5-dione

(S)-tert-Butoxycarbonylamino-((S)-2,2-dimethyl-[1,3]dioxolan-4-yl)-acetic acid

(3R,4S)-1-benzyl-4-hydroxymethyl-3-mesyloxyazetidin-2-one

(R)-1-Benzyl-4-((S)-1,2-dihydroxy-ethyl)-azetidin-2-one