Structural corrections of photinides A, B and their novel derivatives

Relative and absolute structure of phomolide C

Phomolide C (1) was isolated from a fungus Diaporthe sp. being found at Shirakami mountainous area. Although only the planar structure of 1 has been known, our detailed NMR spectroscopic analysis and ECD studies revealed its both relative and absolute configuration.

Roussoellols A and B, tetracyclic fusicoccanes from Roussoella hysterioides

The structures of the tetracyclic fusicoccanes roussoellols A (1) and B (2) from Roussoella hysterioides KT1651 are described. NMR spectroscopic analyses involving NOESY experiments revealed that these molecules possessed unique bent structures that were supported by chemical derivatizations as well as chemical shift comparisons with theoretical shifts based on the density functional theory (DFT) at the EDF2/6-31G* level. Absolute configurations were established by the ECD couplet of positive chirality in both 1 and 2 at vacuum UV (VUV) region, which were further confirmed by successful reproduction of VUVCD spectra using theoretical calculations.