Crystal structure of (5′S,8′S)-3-(2,5-dimethylphenyl)-8-methoxy-3-nitro-1-azaspiro[4.5]decane-2,4-dione

The title compound, C18H22N2O5, was synthesized by nitrification of its enol precursor. The pyrrolidine ring plane adopts a twisted conformation about the C—C bond linking the spiro centre and the C=O group remote from the N atom. It makes dihedral angles of 71.69 (9) and 88.92 (9)°, respectively, with the benzene ring plane and the plane defined by the four C atoms that form the seat of the of the cyclohexane chair. At the spiro centre, the NH group is axial and the C=O group is equatorial with respect to the cyclohexane ring. In the crystal, inversion dimers linked by pairs of N—H...O hydrogen bonds generate R22(8) loops. The dimers are linked by C—H...O interactions, generating a three-dimensional network