Eremanthine (1), an abundant natural substance, was transformed in four steps into diol 5. Hydrogenolysis of 5 (55 psi of H2, Pd/C, 30 min) furnished 7. Hydrogenation of 5 using a low hydrogen pressure (5 psi) and a short reaction time (15 min) led to a mixture of 6 and 7 (3:1). Compounds 6 and 7 were then transformed respectively to the alpha-methylene-gamma-lactones micheliolide (9) and 1(R),10(R)-dihydromicheliolide (8), after elimination of methanol.
anticancer sesquiterpene lactones; eremanthine; micheliolide
