Synergistic use of NMR computation and quantitative interproton distance analysis in the structural determination of neokadcoccitane A, a rearranged triterpenoid featuring an aromatic ring D from Kadsura coccinea

Abstract

Neokadcoccitane A (1), an unprecedented 14(13 → 12):28(14 → 8)-diabeo-3,4-secolanostane triterpenoid possessing an aromatic ring D and an unusual Me-21 orientation, along with two novel 14(13 → 12)-abeo-3,4-seco-norlanostane triterpenoids featuring three- and one-carbon degradation, respectively (2 and 3), were isolated from the roots of Kadsura coccinea. The absolute configuration of 1 was determined by the synergistic use of NMR computation, quantitative interproton distance analysis, and TDDFT ECD calculation, while that of 2 was established using X-ray diffraction. 1 was found to exhibit moderate anti-platelet aggregation activity.