2-[(2R,3R)-3-Bromo-3-((S)-1-hydroxy-ethyl)-2-methylsulfanyl-4-oxo-azetidin-1-yl]-3-methyl-but-2-enoic acid methyl ester

(2S,5R,6R)-6-Bromo-3,3-dimethyl-7-oxo-6-((S)-1-trimethylsilanyloxy-ethyl)-4-thia-1-aza-bicyclo[3.2.0]heptane-2-carboxylic acid methyl ester