(3S,4R)-3-<(tert-Butyldiphenylsilyl)oxy>-4-<(2-methyl-3-buten-2-yl)thio>-2-azetidinone

(2S,5R,6S)-Benzyl 3,3-Dimethyl-7-oxo-6-[[(trifluoromethyl)sulfonyl]oxy]-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate

(3S,4R)-3-<(tert-Butyldiphenylsilyl)oxy>-1-<(2,3-dimethyl-2-butyl)dimethylsilyl>-4-<(2-methyl-3-buten-2-yl)thio>-2-azetidinone

(3S,4R)-3-[(tert-Butyldiphenylsilyl)oxy]-1-[(2,3-dimethyl-2-butyl)dimethylsilyl]-4-[(2-methyl-3-oxo-2-propyl)thio]-2-azetidinone

(3S,4R)-3-[(tert-Butyldiphenylsilyl)oxy]-1-[(2,3-dimethyl-2-butyl)dimethylsilyl]-4-[[4-(benzyloxy)-3-hydroxy-2-methyl-4-nitro-2-butyl]thio]-2-azetidinone