1(R),5(S)-8-[1-(4-cyano-3-fluorobenzyl)-5-imidazolylmethyl]-3-[2-chloro-5-(methanesulfonyloxy)benzyl]-3,8-diaza-2-oxobicyclo[3.2.1]octane

(S)-4-tert-butoxycarbonyl-1-(2,4-dimethoxybenzyl)-5-(2-oxoethyl)-2-piperazinone

1(R),5(S)-8-tert-butoxycarbonyl-3-(2,4-dimethoxybenzyl)-3,8-diaza-2-oxobicyclo[3.2.1]octane

(S)-4-tert-butoxycarbonyl-1-(2,4-dimethoxybenzyl)-5-(2-hydroxyethyl)-2-piperazinone

1(R),5(S)-8-[1-(4-cyano-3-fluorobenzyl)-5-imidazolylmethyl]-3,8-diaza-2-oxobicyclo[3.2.1]octane