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; MTAB N), 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-o1 (C23H29- NO; M HABN) are presented. The compounds MTABN and MHABN crystallize in monoclini c space groups, whereas AABN is orthorhombic. In each of the three structur es, the bicyclic ring system adopts a chair-chair conformation and the phen yl 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.