(2S,5R,6R)-6-[[(2R)-2-[(4-ethyl-2,3-dioxopiperazine-1-carbonyl)amino]-2-phenylacetyl]amino]-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylic acid; (2S,3S,5R)-3-methyl-4,4,7-trioxo-3-(triazol-1-ylmethyl)-4$l^{6}-thia-1-azabicyclo[3.2.0]heptane-2-carboxylic acid
(2S,5R,6R)-6-[[(2R)-2-[(4-ethyl-2,3-dioxo-piperazine-1-carbonyl)amino]-2-phenyl-acetyl]amino]-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylic acid; (2S,3S,5R)-3-methyl-4,4,7-trioxo-3-(triazol-1-ylmethyl)-4$l^{6}-thia-1-azabicyclo[3.2.0]heptane-2-carboxylic acid
(2S,5R,6R)-6-[[(2R)-2-[[(4-ethyl-2,3-dioxo-1-piperazinyl)-oxomethyl]amino]-1-oxo-2-phenylethyl]amino]-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylic acid; (2S,3S,5R)-3-methyl-4,4,7-trioxo-3-(1-triazolylmethyl)-4$l^{6}-thia-1-azabicyclo[3.2.0]heptane-2-carboxylic acid
(2S,5R,6R)-6-[[(2R)-2-[(4-ethyl-2,3-diketo-piperazine-1-carbonyl)amino]-2-phenyl-acetyl]amino]-7-keto-3,3-dimethyl-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylic acid; (2S,3S,5R)-4,4,7-triketo-3-methyl-3-(triazol-1-ylmethyl)-4$l^{6}-thia-1-azabicyclo[3.2.0]heptane-2-carboxylic acid
(2S,5R,6R)-6-[[(2R)-2-[(4-ethyl-2,3-dioxo-piperazin-1-yl)carbonylamino]-2-phenyl-ethanoyl]amino]-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylic acid; (2S,3S,5R)-3-methyl-4,4,7-trioxo-3-(1,2,3-triazol-1-ylmethyl)-4$l^{6}-thia-1-azabicyclo[3.2.0]heptane-2-carboxylic acid