6α-bromopenicillanic acid methyl ester

3(S)-<1(R)-<<(phenoxymethyl)carbonyl>oxy>ethyl>-4(R)-<(2,5-dimethoxyphenyl)sulfonyl>-1-<1-(methoxycarbonyl)-2-methyl-1-propen-1-yl>azetidin-2-one

3(S)-bromo-4(R)-<(2,5-dihydroxyphenyl)sulfonyl>-1-<1-(methoxycarbonyl)-2-methyl-1-propen-1-yl>azetidin-2-one

6α-Bromopenicillanic acid 1,1-dioxide methyl ester

3(S)-bromo-4(R)-<(2,5-dimethoxyphenyl)sulfonyl>-1-<1-(methoxycarbonyl)-2-methyl-1-propen-1-yl>azetidin-2-one