A series of ureas derived from 3-methyl-2,4-diphenyl-3-azabicyclo[3.3.1]nonan-9α-amine were synthesized and studied by IR, Raman, 1 H and 1 3 C NMR spectroscopy. These compounds adopt, in CDCl 3 , a preferred flattened chair-chair conformation with the cyclohexane ring more flattened than the piperidine moiety and the N-CH 3 groups in equatorial positions. IR and 1 H and 1 3 C NMR data show the presence of two conformations at the urea unity. These results are supported by molecular modeling studies.