4(R)-<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(S)-hydroxy-6-methylheptanamide

N-L-isoleucyl-2-pyridylmethylamine

sodium 4(S)-<(tert-butoxycarbonyl)amino>-2,2-difluoro-3(S)-<(4-methoxyphenyl)amino>-6-methylheptanoate

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