Molecular structures and conformations of three 3-azabicyclononanes

The structure, conformation, molecular geometry and the mode of packing of 7‐tert‐butyl‐N‐methyl‐2,4‐diphenyl‐3‐azabicyclo[3.3.1]nonane (C25H33N; MTABN), N‐acetyl‐2,4‐diphenyl‐3‐azabicyclo[3.3.1]nonane (C22H25NO; AABN) and N‐methyl‐2,4‐bis(2‐methylphenyl)‐3‐azabicyclo[3.3.1]nonan‐9‐ol (C23H29NO; MHABN) are presented. The compounds MTABN and MHABN crystallize in monoclinic space groups, whereas AABN is orthorhombic. In each of the three structures, the bicyclic ring system adopts a chair–chair conformation and the phenyl rings are in equatorial orientation with respect to the piperidine ring. In AABN, apart from the van der Waals forces, weak intermolecular C—H⋯O type interactions are involved in the packing.