HIGH-PRECISION CALCULATION OF 1H AND 13C NMR CHEMICAL SHIFTS OF STRICHNINA ALKALOIDS

The calculation of 1H and 13C NMR chemical shifts in the series of strychnine alkaloids using the Purdue-Burke-Ernzerhof functional, PBE0, with segmented Jensen basis sets of threefold splitting level pcSseg-2 and pcseg-2, PBE0 / pcSg-2 // pcseg-2.

Long range deuterium isotope effects on 13C NMR chemical shifts of 2-alkanones in CD3OD solutions of imidazolium acetate ionic liquids

Long range deuterium isotope effects on the carbon spectral pattern in 2-hexanone reveal the existence and distribution of H/D isotopomers.

1H AND 13C NMR SPECTRA OF STRYCHNOS ALKALOIDS: SELECTED NMR UPDATES

The PBE0/pcSseg-2//pcseg-2 calculations of 1H and 13C NMR chemical shifts were performed for a classical series of 12 Strychnos alkaloids (except for the earlier studied parent strychnine), namely akuammicine, isostrychnine, rosibiline, tsilanine, spermostrychnine, diaboline, cyclostrychnine, henningsamide, strychnosilidine, strychnobrasiline, holstiine, and icajine. It was found that calculated 1H and 13C NMR chemical shifts demonstrated markedly good correlations with available experimental data characterized by a mean absolute error of 0.22 ppm for the range of 8 ppm for protons and 1.97 ppm for the range of 180 ppm for carbons. Complimentary, present results provide essential NMR update and fill a gap in the NMR data of this distinguished group of the vitally important natural products.