2-(9H-Fluoren-9-yl)-4-(4-fluoro­anilino)-4-oxo­butanoic acid

In the title compound, C₂₃H₁₈FNO₃, the tricyclic 9-fluorenyl system is approximately planar (r.m.s. deviation = 0.0279 Å). The N—C(=O) bond length is comparatively short [1.359 (3) Å], which is typical for such conjugated systems. The N atom has a planar configuration [sum of bond angles= 359.8°] due to conjugation of its lone pair with the π-system of the carbonyl group. In the crystal, a three-dimensional network is formed through N—H...O and O—H...O hydrogen bonds between the amide and carb­oxy­lic acid groups and carbonyl O-atom acceptors.

2,6-Dimethyl-4-oxo-3-oxatri­cyclo­[5.2.1.0^2,6]decane-1-carboxamide

In the title compound, C₁₂H₁₇NO₃, which was synthesized by Wagner–Meerwein rearrangement of the N-nitro­imine, the ring-junction C—C bond length is comparatively long [1.573 (2) Å] due to a steric repulsion between the methyl groups at these atoms, which also leads to an increase in the C—C—C angles along this C₄ chain [118.10 (13) and 115.04 (15) °, respectively]. In the crystal, N—H...O—C and N—H...O=C hydrogen bonds are formed between the amide group and the two O-atom acceptors of the lactone group, forming a chain along [001].