(2R,4R,Z)-2-(carboxymethyl)-5-(2-hydroxyethylidene)-3-((2R,5R,Z)-3-(2-hydroxyethylidene)-7-oxo-4-oxa-1-azabicyclo[3.2.0]heptane-2-carbonyl)oxazolidine-4-carboxylic acid
(2R,4R,Z)-2-(carboxymethyl)-5-(2-hydroxyethylidene)-3-((2R,5R,Z)-3-(2-hydroxyethylidene)-7-oxo-4-oxa-1-azabicyclo[3.2.0]heptane-2-carbonyl)oxazolidine-4-carboxylic acid