Structure Revision of Pyranoxanthones via DFT-Assisted ¹³C NMR Analysis and NAPROC-13 Platform: Diagnostic Markers and Discovery of Unreported Natural Products.

ABSTRACT: The structures of 47 natural and synthetic pyranoxanthones, previously misassigned in the literature, were revised using the NAPROC-13 platform in combination with DFT-based ¹³C NMR calculations. Structural misassignments primarily involved incorrect prenyl group localization or misplacement of the oxygen atom involved in the pyran ring. NAPROC-13 searches frequently revealed alternative, structurally distinct compounds sharing identical ¹³C NMR data, or instances where the same compound had been reported with divergent data sets. DFT-calculated chemical shifts confirmed the revised structures, which included six previously unreported natural products. Systematic deviations between calculated and experimental values were observed for carbons adjacent to the carbonyl a

SUBMITTER: Sanchez-Martinez HA 

PROVIDER: S-EPMC12706791 | biostudies-literature | 2025 Dec

REPOSITORIES: biostudies-literature