¹H and ¹³C NMR spectra of Strychnos alkaloids: Selected NMR updates

Abstract

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 the calculated 1H and 13C NMR chemical shifts show markedly good correlations with available experimental data, as 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. Complementarily, the present results provide essential NMR update and fill a gap in the NMR data of this distinguished group of vitally important natural products.

Computational NMR of Carbohydrates: Theoretical Background, Applications, and Perspectives

“…Different LDBS schemes were systematically employed for the calculation of NMR parameters at the DFT and non-empirical levels of theory in a number of recent publications by Rusakov et al [ 68 , 69 , 70 , 71 , 72 , 73 , 74 , 75 , 76 , 77 , 78 , 79 ] and Semenov et al [ 80 , 81 , 82 , 83 , 84 , 85 ], as well as in numerous publications by different authors, which are not cited herewith in full in view of their multiplicity.…”

Azo‐hydrazone molecular switches: Synthesis and NMR conformational investigation

“…This combination was recently recommended for larger organic molecules. [15][16][17][18][19][20] In all nuclear shielding calculations, the gauge including atomic orbitals (GIAO) [21][22][23][24][25] formalism was used.…”

Computational NMR of natural products: On the way to super large molecules exemplified with alasmontamine A

“…Theoretical calculation of 13 C nuclear magnetic resonance (NMR) chemical shifts provides a powerful tool in structural elucidation of organic molecules, natural products, carbohydrates, and biochemical species. [1][2][3][4][5] Continuing our very recent survey of large natural products with multiple asymmetric centers, [6][7][8][9][10][11] current study is focused on the huge tetrakis monoterpene indole alkaloid, alasmontamine A, which is shown below in Figure 1.…”