AN EFFICIENT SYNTHESIS OF CERBINAL, A 10 PI AROMATIC IRIDOID

Cerbinal (1)1) isolated from either Cerbera manghas L. or Gardenia jasminoides Ellis, has been recognized by its characteristic DELTA-3,5,7,9-tetraene aromatic 10 pi-system. This unusual iridoid structure is also found in baldrinal (2)2) and viburtinal (3). 3) Compound 3 has been traditionally used as a spasmolytic, while 2 was recently found to exhibit potent cytotoxicity against HTC hepatoma cells and anti-tumor activities against KREBS II ascitic tumor. 2) Those biological activities as well as an unusual iridoid structure made us investigate a synthetic scheme toward 1, a key compound for other natural and unnatural iridoid 10 pi-systems.