Bafoudiosbulbins F and G, further clerodane diterpenoids from <i>Dioscorea bulbifera</i> L. var <i>sativa</i> and revised structure of Bafoudiosbulbin B

From the bulbils of <i>Dioscorea bulbifera</i> L. var <i>sativa</i>, two clerodane diterpenoids, Bafoudiosbulbins F (<b>1</b>) and G (<b>2</b>), together with five known compounds: Bafoudiosbulbins A–C, 3,5,4′-trihydroxy-3′-methoxybibenzyl, and kaempferol were isolated. Their structures were established by spectroscopic techniques, including ¹H,¹³C NMR, NOESY, ROESY, COSY, TOCSY, HSQC, and HMBC. The relative stereochemistry of compounds <b>1</b> and <b>2</b> was assigned on the basis of X-ray crystallographic diffraction analysis. Furthermore, the structure of Bafoudiosbulbin B was revised using extensive 2D NMR techniques as well as chemical transformation.