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(2007/10/02)(2S,3S)-3-[(S)-2-(tert-Butyl-diphenyl-silanyloxy)-1-hydroxy-ethyl]-1-(4-methoxy-phenyl)-4-oxo-azetidine-2-carboxylic acid tert-butyl ester
[[(2R,3R)-3-(tert-Butyl-diphenyl-silanyloxymethyl)-oxiranecarbonyl]-(4-methoxy-phenyl)-amino]-acetic acid tert-butyl ester
(2S,3S)-3-((S)-1,2-Dihydroxy-ethyl)-1-(4-methoxy-phenyl)-4-oxo-azetidine-2-carboxylic acid tert-butyl ester
(2S,3S)-1-(4-Methoxy-phenyl)-3-(S)-oxiranyl-4-oxo-azetidine-2-carboxylic acid tert-butyl ester