4(S)-<1(S)-<(tert-butyloxycarbonyl)amino>-3-methylbutyl>-3,3-difluoro-1-(methoxyphenyl)-2-azetidinone

N-(4-methoxyphenyl)-4(S)-<(tert-butyloxycarbonyl)amino>-2,2-difluoro-3(R)-hydroxy-6-methylheptanamide

N-(4-methoxyphenyl)-4(S)-<(tert-butyloxycarbonyl)amino>-2,2-difluoro-3(S)-hydroxy-6-methylheptanamide

sodium 4(S)-<(tert-butyloxycarbonyl)amino>-2,2-difluoro-3(R)-hydroxy-6-methylheptanoate

Sodium; (3S,4S)-4-tert-butoxycarbonylamino-2,2-difluoro-3-hydroxy-6-methyl-heptanoate