The absolute configuration of 7 was determined on the basis of its structural similarity to abundisporin E (6) and by comparing their NOE correlations with those obtained from 1 that established its absolute configuration as (4R,5R,9R,10S). This absolute configuration was also confirmed independently by TDDFT-ECD calculations (Figure ). The ωB97X/TZVP PCM/MeOH re-optimization of the initial 18 MMFF conformers of (4R,5R,9R,10S)-7 resulted in