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

Abstract

Nuclear magnetic resonance (NMR) spectroscopy can provide detailed information about the chemical structure and stereochemistry of a molecule. However, this technique alone may not always be sufficient to assign with confidence the relative configuration of a secondary metabolite. In some cases, additional experiments, such as the Density Functional Theory (DFT) calculation of the chemical shifts for the molecule, may be necessary to support the assignment. An endoperoxide (1) isolated from Plakortis angulospiculatus has a structure containing four stereogenic centers. The stereochemistry of 1 was proposed based on the biogenetic pathway and optical rotation correlations. Herein, we describe the structure analysis of the natural 1 by quantum NMR calculations for the first time.