Calvin M. Lee, A. Beckett, J. Sugden
1966
Citations
0
Influential Citations
3
Citations
Journal
Tetrahedron
Abstract
Abstract Seven N-substituted-4-(cyanophenylmethylene)piperidines were synthesized by the condensation of N-substituted-4-piperidones with ring substituted benzyl nitriles. Hydrolysis of modification of the cyano group of these compounds was unsuccessful. Their structures were confirmed by analyses, and IR and UV data; spectral evidence indicates that the benzene ring is out of the plane of maximum conjugation due to non-bonded interaction between the ortho hydrogens of the phenyl ring and methylene protons of the heterocyclic ring. The NMR spectrum of N-benzyl-4-(cyanophenylmethylene)piperidine is unexpectedly simple with the eight ring protons appearing as a four proton singlet (2·46 ppm δ) and a symmetrical four-proton multiplet (2·74 ppm). the piperidine ring shows ready conformational interchange and there is fortuitous coincidence of the long range, anisotropic and inductive effects of the phenyl ring, nitrile group, double bond and substituted nitrogen atom so that the four protons on the same side as the phenyl ring become equivalent and form an A 4 singlet. The protons on the same side as the cyano group have different chemical shifts and interact to produce an A 2 B 2 multiplet. The NMR spectra of compounds related to N-benzyl-4-(cyanophenylmethylene)piperidine confirm these conclusions.