Stereochemical revision of xylogranatin F by GIAO and DU8+ NMR calculations

Abstract

This manuscript describes predicted NMR shifts for the limonoid natural product xylogranatin F. The 1 H and 13 C NMR shifts of four diastereomers were evaluated by GIAO and hybrid DFT/parametric DU8+ methods. The results of the 1 H and 13 C NMR calculations for both the GIAO method and the DU8+ calculations suggest the revised structure that was recently reassigned by chemical synthesis. Furthermore, we show that while DU8+ provides superior accuracy with less computation time, GIAO points to the correct structure with more distinguishable data in this case study.

Pitfalls in the structural elucidation of small molecules. A critical analysis of a decade of structural misassignments of marine natural products

“…Shortly thereafter, though using GIAO and DU8+ NMR calculations, the revised structure 141 was further verified to be the closest to the authentic xylogranatin F among its four possible diastereomers. 169 The wrong configurational of xylogranatins is reminiscent of the one of tagalenes ( 130 and 131 ). Also, in this case, a bisecting and therefore ambiguous relationship between a proton and the substituents on adjacent carbon was overlooked in the analysis of NOE correlations.…”

Research progress of meliaceous limonoids from 2011 to 2021

“…The structures of (+)-xylogranatin F and (+)-xylogranatin G were revised by total synthesis 458 as well as GIAO and DU8+ NMR calculations. 459 By comparing the NMR data, the structure of their analogue, hainangranatumin G ( 88 ), has also been revised.…”

NMR of Natural Products as Potential Drugs

“…Calculations are a useful tool in structure elucidation of natural products [ 35 , 36 ]. Comparison with calculated mostly 13 C chemical shifts can also be used to correct structures [ 37 ].…”