2,4-Bis(4-ethoxyphenyl)-7-methyl-3-aza-bicyclo-[3.3.1]nonan-9-one

The mol-ecule of the title compound, C 25H 31NO 3, exists in a twin-chair conformation with an equatorial orientation of the 4-eth-oxy-phenyl groups, as observed for its ortho isomer [Parthiban, Ramkumar, Park & Jeong (2011b ), Acta Cryst. E67, o1475-o1476]. The methyl and 4-eth-oxy-phenyl groups are also equatorially oriented on the bicycle, as in the ortho analogue. In particular, although the cyclo-hexa-none ring deviates from an ideal chair, the piperidone ring is closer to an ideal chair, whereas in the ortho isomer both rings are significantly puckered and deviate from ideal chairs. The 4-eth-oxy-phenyl groups on both sides of the secondary amine group are oriented at an angle of 26.11 (3)° with respect to each other, but the 2-eth-oxy-phenyl groups in the ortho isomer are oriented by less than half this [12.41 (4)°]. In contrast to the absence of any significant inter-actions in the crystal packing of the ortho isomer, the title compound features N - H⋯O inter-actions, linking the mol-ecules along the b axis.