2,4-Bis(4-ethoxyphenyl)-1-methyl-3-azabicyclo[3.3.1]nonan-9-one

In the title compound, C25H30NO3, a crystallographic mirror plane bisects the molecule. Although it is a positional isomer of 2,4-bis(4-ethoxyphenyl)-7-methyl-3-azabicyclo[3.3.1]nonan-9-one [C25H31NO3, Mr = 393.51; Park et al. (2012c). Acta Cryst. E68, o779–780], its molecular weight is 392.50 due to the 50:50 ratio of the methyl group at bridgehead C atoms. However, the title compound exists in the same twin-chair conformation as its 7-methyl isomer. Also, the 4-ethoxyphenyl groups are equatorially oriented on the bicycle as in its isomer. In the title compound, the cyclohexanone ring deviates from an ideal chair (total puckering amplitude QT = 0.5390 Å) and the piperidone ring is closer to an ideal chair (QT = 0.6064 Å). These QT values are very similar to those of its isomer. Even though a center of symmetry passes through the 7-methyl analog, the benzene rings are oriented 26.11 (3)° with respect to each other, whereas the orientation is 53.10 (3)° for the title compound. The title compound exhibits intermolecular N—H...O interactions [H...A = 2.25 (2) Å, versus 2.26 (2) Å for the analog]