0000000000231147
AUTHOR
Matthias Niemitz
Complete Spectral Analysis of the1H NMR 16-Spin System of β-Pinene
The complete analysis of the 1H NMR spectrum of β-pinene, (1S)-(-)-6,6-dimethyl-2-methylenebicyclo[3.1.1]heptane, which is of the ABCDEFGHIJX3Y3 type, is reported and earlier results are corrected. The vicinal coupling constants, 3J(H,H), are compared with the theoretical values calculated by using the Altona and co-workers’ equations for the structure derived by molecular modelling. The results were applied to the conformational analysis of β-pinene. © 1997 John Wiley & Sons, Ltd.
Comprehensive Strategy for Proton Chemical Shift Prediction: Linear Prediction with Nonlinear Corrections
A fast 3D/4D structure-sensitive procedure was developed and assessed for the chemical shift prediction of protons bonded to sp3carbons, which poses the maybe greatest challenge in the NMR spectral parameter prediction. The LPNC (Linear Prediction with Nonlinear Corrections) approach combines three well-established multivariate methods viz. the principal component regression (PCR), the random forest (RF) algorithm, and the k nearest neighbors (kNN) method. The role of RF is to find nonlinear corrections for the PCR predicted shifts, while kNN is used to take full advantage of similar chemical environments. Two basic molecular models were also compared and discussed: in the MC model the desc…