First total syntheses of kanjone and its natural analogues.

Kanjone (1), a bioactive furanoflavone and a potent biomolecule, was first isolated from Pongamia pinnata (L.). Herein, we have developed two approaches to synthesize kanjone as well as its natural analogues 6-methoxyisopongaglabol (2) and 6,3'-dimethoxy-[2″,3″:7,8]furanoflavone (3) starting from khellin and 3-hydroxy-4-methoxy-benzaldehyde, respectively.