(-)-3β-((1S)-1-hydroxyethyl)-4α-<3-<<(p-nitrobenzyl)oxy>carbonyl>-2-oxopropyl>azetidin-2-one

(-)-3β-<(1S)-1-<(tert-butyldimethylsilyl)oxy>ethyl>-4α-<3-<<(p-nitrobenzyl)oxy>carbonyl>-2,2-(ethylenedioxy)propyl>azetidin-2-one

(-)-4α-<3-(ethoxycarbonyl)-2,2-(ethylenedioxy)propyl>-3β-((1S)-1-hydroxyethyl)azetidin-2-one

4-[(R)-3-((R)-1-Formyloxy-ethyl)-4-oxo-azetidin-2-yl]-3-oxo-butyric acid 4-nitro-benzyl ester

(+)-1-(tert-butyldimethylsilyl)-3β-<(1S)-1-<(tert-butyldimethylsilyl)oxy>ethyl>-4α-<3-(ethoxycarbonyl)-2,2-(ethylenedioxy)propyl>azetidin-2-one

(R,Z)-2-(2-(2-ethoxy-2-oxoethyl)-1,3-dioxolan-2-yl)-N-(1-phenylethyl)ethan-1-imine oxide

benzyl (+)-(3,4-cis,4,5-trans)-3-<3-(ethoxycarbonyl)-2,2-(ethylenedioxy)propyl>-5-methyl-2-((1R)-1-phenylethyl)isoxazolidine-4-carboxylate

ethyl 3,3-(ethylenedioxy)-4-formylbutyrate

diethyl 2-acetyl-3-benzylamino-2-pentenedioate