Stereochemical studies of some t-3-methyl-r-2,c-6-diphenylpiperidin-4-one azine derivatives

H-1 and C-13 NMR spectra are recorded for six t-3-methyl-r-2,c-6-diphenylpiperidin-4-one azine derivatives 8-13 in CDCl3 and analysed. The proton spectra reveal the presence of two isomers in solution for the azines 12,13 and 8 and one isomer for 9-11. In all azines the N-N single bond is found to be anti with respect to methyl group at C-3 in the piperidone ring and the two C=N bonds are trans with respect to N-N single bond (s-trans form). In the azines 9-11 the azomethine proton is found to be syn with respect to N-N bond. The other azines 12,13 and 8 exist as a pair of diastereoisomers in solution.