Non-empirical calculations of NMR indirect carbon-carbon coupling constants. Part 12—Aliphatic and alicyclic oximes

Abstract

One-bond carbon-carbon coupling constants were calculated in a series of nine aliphatic and alicyclic oximes at the SOPPA (second-order polarization propagator approach) level in good agreement with the available experimental data, and several unknown couplings were predicted with high reliability. The experimental difference between J(C,C) of the corresponding carbon-carbon bonds in cis and trans orientations to the nitrogen lone pair is very well reproduced at the SOPPA level, and this provides an additional tool in the configurational assignment at the C=N bond in oximes and related systems.

CH···N and CH···O intramolecular hydrogen bonding effects in the 1H, 13C and 15 N NMR spectra of the configurational isomers of 1‐vinylpyrrole‐2‐carbaldehyde oxime substantiated by DFT calculations

“…Very recently, the calculations of spin-spin coupling constants in the various 2-substituted 1-vinylpyrroles [18,25] and oximes [10,26] by means of second-order polarization propagator approach (SOPPA) yielded an adequate reproduction of the experimental data. Such computations demand application of the specified basis set for each sort of the coupled nuclei.…”

“…[27] In the present work, all coupling as well as shielding constants were simultaneously obtained from calculations in the DFT framework employing the hybrid B3LYP functional since it ensures the most reliable results. [10,26] The calculated values of the 1 H-1 H, 13 C-1 H, 15 N-1 H coupling constants are summarized in Table 8.…”

GIAO‐DFT calculation of 15N NMR chemical shifts of Schiff bases: Accuracy factors and protonation effects

“…Many chemical transformations and rearrangements of diverse imines (in particular, oximes) utilized in the synthesis of azoles and larger nitrogen‐containing heterocycles (see classical paper by Trofimov and Mikhaleva together with some more recent contributions from this team) occur stereoselectively, which makes the problem of stereoelectronic effects at the C═N bond to be of crucial importance. In this connection, our earlier and later experimental and theoretical studies of imines received a new impact, especially in line with the recent breakthrough in the NMR‐oriented theory and computation including, in particular, general computational approaches for 15 N NMR chemical shifts …”

“…synthesis of azoles and larger nitrogen-containing heterocycles (see classical paper by Trofimov and Mikhaleva [10] together with some more recent contributions [11][12][13][14][15][16][17][18][19] from this team) occur stereoselectively, which makes the problem of stereoelectronic effects at the C═N bond to be of crucial importance. In this connection, our earlier [20,21] and later [7,[22][23][24] experimental and theoretical studies of imines received a new impact, especially in line with the recent breakthrough in the NMR-oriented theory and computation [25][26][27][28][29][30][31][32][33][34][35][36][37] including, in particular, general computational approaches for 15 N NMR chemical shifts. [38,39] An interest in 15 N NMR chemical shifts stemmed mainly from the early experimental papers by Witanowski and coworkers (for the most comprehensive compilations, see reviews [40][41][42][43][44] ), in particular, those dealing with protonation effects.…”

Evaluating the accuracy of theoretical one‐bond 13C─13C scalar couplings and their ability to predict structure in a natural product

“…[2,11,18,24,28,[52][53][54][55][56][57][58] Recent theoretical work often relies upon the secondorder polarization propagator approximation technique [8,11,12,20,22,24,30,31,39,56,59] or density functional theory (DFT) computations [13,14,17,19,23,[26][27][28]33,[36][37][38]41,43,45,54,55,57,60] that employ the EPR-III [61,62] basis set. [3,26,28,30,39,53,54] The EPR-III basis, although originally developed to predict hyperfine coupling constants in electron ...…”