(5R)-6c-azido-3,3-dimethyl-7-oxo-5-phenyl-(5rH)-4-thia-1-aza-bicyclo[3.2.0]heptane-2-carboxylic acid benzyl ester
(5R)-3,3-dimethyl-4t,7-dioxo-6c-(2-phenoxy-acetylamino)-5-phenyl-(5rH)-4λ4-thia-1-aza-bicyclo[3.2.0]heptane-2c-carboxylic acid benzyl ester
(5R)-3,3-dimethyl-4t,7-dioxo-6t-(2-phenoxy-acetylamino)-5-phenyl-(5rH)-4λ4-thia-1-aza-bicyclo[3.2.0]heptane-2c-carboxylic acid benzyl ester
(5R)-3,3-dimethyl-7-oxo-6c-(2-phenoxy-acetylamino)-5-phenyl-(5rH)-4-thia-1-aza-bicyclo[3.2.0]heptane-2c-carboxylic acid benzyl ester
(5R)-3,3-dimethyl-7-oxo-6t-(2-phenoxy-acetylamino)-5-phenyl-(5rH)-4-thia-1-aza-bicyclo[3.2.0]heptane-2c-carboxylic acid benzyl ester