STEREOCHEMISTRY OF 4-CYANO-4-PHENYLAMINO-R-2, C-6-DIPHENYLPIPERIDINES

The stereochemistry of four N-phenylaminonitriles 6-9 derived front r- 2, c-6-diphenylpiperdin-4-ones 2-5 has been determined using NMR spect ral techniques and DAERM (Dihedral Angle Estimation by the Ratio Metho d) calculations. They prefer chair conformations with the cyano group in axial position and the phenylamino group being in the equatorial or ientation. The presence of alkyl substituents at C-3 position in the a minonitriles 7-9 causes a flattening at C-3 end. The predominant forma tion of one of the two possible isomers has been rationalized by invok ing the Cieplak's concept of pi-facial selectivity in which the nucleo philic attack of cyanide ion at the imine carbon takes place from the axial side.