1-aza-10-carbomethoxy-3-(2-carbomethoxyethyl)-5-hydroxy-2-oxo-bicyclo(4.4.0)dec-3,5-diene

1,2,3,5-tetrahydro-9-hydroxy-6-oxo-4-<(phenylmethoxy)carbonyl>-2(H)-quinolizine-7-propanoic acid

3-(9-hydroxy-4-(methoxycarbonyl)-6-oxo-1,3,4,6-tetrahydro-2H-quinolizin-7-yl)propanoic acid

1-aza-10-carbomethoxy-3-(2-carbomethoxyethyl)-2,5-dioxobicyclo<4.4.0>decane

methyl 6-methoxy-1-(2-(3-methoxy-3-oxopropyl)hex-4-ynoyl)piperidine-2-carboxylate