Synthesis and spectral studies of some polysubstituted cyclohexanone oximes; DFT approach for the optimization

Abstract

A series of t(3)-aryl-r(2), c(4)-bis(isopropoxycarbonyl)-c(5)-hydroxy-t(5)-methyl cyclohexanone oximes 8-14 were synthesized by condensing corresponding cyclohexanones with sodium acetate and hydroxylamine hydrochloride in ethanol solvent. For all synthesized compounds 1H and 13C NMR were recorded in CDCl3. HOMOCOSY, HSQC, HMBC, and NOESY spectra have been recorded for the representative compound in the series using CDCl3 as solvent. The coupling constants for all the compounds were calculated and it suggests that all the synthesized compounds be in normal chair conformation. The orientations of all substituents were at an equatorial position except hydroxy at C-5. All the synthesized cyclohexanone oximes were in E configuration about the C and N double bond. In CDCl3 the hydroxy proton at C-5 prefers to be anti to C(5)-C(6) bond. Long-range coupling was observed between the hydroxy proton at the C-5 and axial methylene proton at C-6 by having a “W” arrangement. The optimized molecular structure of compound 14 has been performed by using the DFT method with a B3LYP/6-311++G(d,p) basis set. The Non-linear optical (NLO) activity of compound 14, the linear polarizability, dipole moment, and first-order hyperpolarizability were derived from molecular polarizability by the theoretical-based calculations. To study the intramolecular charge transfer, bonding (Lewis), and anti-bonding (Non-Lewis) structural calculation was carried out using NBO analysis. The charge transfer occurring within molecule 14 was analyzed from the HOMO-LUMO calculation. The molecular electrostatic potential (MEP) surface shows the active sites present in the molecule.