Bafoudiosbulbin H, a new clerodane diterpene from the flowers of Dioscorea bulbifera L. var sativa

Abstract A new clerodane diterpenoid, bafoudiosbulbin H ( 1 ), was isolated from the flowers of Dioscorea bulbifera L. var sativa . Its acetylation using acetic anhydride-pyridine and catalytic amount of 4-DMAP at 60 °C yielded bafoudiosbulbin H acetate ( 2 ) together with a clerodane with an unprecedented acylation pattern (bafoudiosbulbin H1, 3 ). The reaction of the known bafoudiosbulbin G ( 4 ) in the same conditions yielded demethylbafoudiosbulbin G ( 5 ). Structural elucidation of 5 led to the revision of the stereochemistry previously assigned to 4 . Structures were elucidated using spectroscopic techniques, including 1D and 2D NMR ( 1 H, 13 C, HSQC, COSY, HMBC, ROESY, NOESY) and mass spectrometry (HRESIMS).