Figure 5
From: 2′-Epi-uscharin from the Latex of Calotropis gigantea with HIF-1 Inhibitory Activity
Interconverting between uscharin (1) and 2′-epi-uscharin (2) by intramolecular hemiketal folding of glycosidulose intermediate under a) mild acidic condition, 1% formic acid or b) mild alkaline condition, 1% ammonium hydroxide.
