Combined application of DP4+ and ANN‐PRA to determine the relative configuration of natural products: The alpha‐bisabol case study

Abstract

The combination of computational methods and experimental data from Nuclear Magnetic Resonance (NMR) is a considerably valuable tool in the elucidation of new natural product structures and, also, in the structural revision of previously reported compounds. Until recently, only classical statistical parameters were used, for example, linear correlation coefficient (R 2 ), mean absolute error (MAE), or root mean square deviation (RMSD), as a way to statistically "validate" the structure pointed out by experimental NMR spectra. Regarding the resolution of the relative configuration of organic molecules, novel tools were available in the last few years to assist in the NMR elucidation process. The most relevant are DP4+, which is based on a Bayesian probabil-

Are we still chasing molecules that were never there? The role of quantum chemical simulations of NMR parameters in structural reassignment of natural products

“…The application of DP4+ methodology to a dataset of 48 organic compounds demonstrated its capacity to provide more accurate results than the original DP4 formulation. Subsequent to its development, DP4+ has been extensively employed to the elucidation and correction of natural products structures (Batista et al, 2019;Martorano et al, 2020;Marcarino et al, 2022;Silva et al, 2022;Santos et al, 2022).…”

Combining the power of DP4+ and ANN-PRA analysis on stereochemical assignments: structural validation of bioactive cyclic peroxide from the marine sponge Plakortis angulospiculatus

“…Due to the points raised above and based on the fact that our research group has been dedicated to applying and developing new tools for the structural elucidation of complex natural products by means of quantum chemical calculations of NMR parameters, 6,16–28 following our continuous interest in the field, in this article, we discuss the first analysis of the stereoisomers of the bioactive cyclic peroxide from the marine sponge Plakortis angulospiculatus (Fig. 1).…”

“…Furthermore, attempting to determine the absolute stereochemistry based on comparisons of experimental optical rotation (OR) data with those described for analogous molecules is not always applicable since similar molecules, containing the same absolute stereochemistry, have been reported with oppositely signed OR values. 4,[13][14][15] Due to the points raised above and based on the fact that our research group has been dedicated to applying and developing new tools for the structural elucidation of complex natural products by means of quantum chemical calculations of NMR parameters, 6,[16][17][18][19][20][21][22][23][24][25][26][27][28] following our continuous interest in the field, in this article, we discuss the first analysis of the stereoisomers of the bioactive cyclic peroxide from the marine sponge Plakortis angulospiculatus (Fig. 1).…”