SYNTHESIS AND CONFORMATIONAL ANALYSIS OF SOME CYANOMETHYLENE DERIVATIVES OF PIPERIDINES
A. Manimekalai, J. Anusuya, J. Jayabharathi
Keywords: molecular conformations, saturated heterocycles, six-membered heterocycles, computations, NMR spectra, mass spectra, A1, 3 strain
Pages: 465-475
Abstract
Five 4-dicyanomethylene derivatives 6-10, N-cyanoacetyl-cis-2,6-diphenylpiperidin-4-one 11 and 4-cyano(ethoxycarbonyl)-methylene-cis-2,6-bis(o-chlorophenyl)piperidine 12 were synthesised by condensing the appropriate piperidin-4-ones 13-17 with malononitrile/ethylcyanoacetate and their 1H and 13C NMR spectra were recorded. The 1H-1H COSY spectrum for 6 and NOESY spectra for 8, 10 and 11 were also recorded. Based on coupling constants and the results obtained from NOESY spectra boat conformation for 10 and epimerised chair conformations for 8 and 9 have been proposed. Other derivatives adopt normal chair conformations. Theoretical calculations and the 1H and 13C chemical shifts also support the above conformations. Mass spectra were also recorded for 6-12.
|
