SYNTHETIC STUDIES ON QUASSINOIDS - TOTAL SYNTHESIS AND BIOLOGICAL EVALUATION OF (-DES-D-CHAPARRINONE())

A total synthesis of des-D-chaparrinone (2), which lacks the ring D de lta-lactone of (-)-chaparrinone (1) has been developed. The synthesis commences with the known, readily available tricyclic ketone 3 (R = Me ). Elaboration-of the configuration at C(5) followed by resolution of 6 employing 2(R),3(R)-2,3-butanediol gave rise to 9. Installation of t he ring;C functionality provided 15 which was transformed into tricycl ic diketone 25. Introduction of the ring A functional groups afforded 29, which upon exposure to aluminum trichloride and sodium iodide gave rise directly to (+)-des-D-chaparrinone (2). Biological studies revea led that (+)-2 was devoid of any solid tumor activity.