2-(3,5-Dioxo-4-aza­tri­cyclo­[5.2.1.0(2,6)]dec-8-en-4-yl)acetic acid

The asymmetric unit of the title compound, C(11)H(11)NO(4), contains two mol­ecules, A and B, with different conformations: in mol­ecule A, the norborne and carb­oxy­lic acid groups lie to the same side of the heterocycle, whereas in a mol­ecule B, they lie on opposite sides. In the crystal, the A mol­ecules form R (2) (2)(8) carb­oxy­lic acid inversion dimers, linked by pairs of O—H⋯O hydrogen bonds. The B mol­ecules link to one of the ketone O atoms of the A mol­ecule by an O—H⋯O inter­action, resulting in tetra­mers (two A and two B mol­ecules). The tetra­mers are linked by weak C—H⋯O inter­actions, generating a three-dimensional network.