(3R,4S)-1-Benzyl-3-benzyloxy-4-((1S,2S)-1,2-dihydroxy-2-phenyl-ethyl)-azetidin-2-one

(3R,4S)-1-Benzyl-3-benzyloxy-4-((E)-2-p-tolyl-vinyl)-azetidin-2-one

(S)-1-Benzyl-4-[2-(4-methoxy-phenyl)-ethyl]-azetidine-2,3-dione

(3R,4S)-1-Benzyl-4-ethyl-3-hydroxy-azetidin-2-one

(S)-3-Benzyl-4-propyl-oxazolidine-2,5-dione