Inversão da fusão lactônica em derivados da Eremantina e síntese do Miqueliolido

Abstract

This study describes the trans-cis inversion of the lactonic fusion of Eremantine derivatives. Thus, the carboxylic salts of compounds 40, 43, 70 and 71 were synthesized and their hydroxy groups at the 6 position were activated by the formation of the respective mesylates (MsCI, Et3N, THF), which underwent further displacement by the carboxylate group. Methods to deoxygenate the 9 position of the 46 derivative were also investigated aiming at the synthesis of the natural sesquiterpene lactone - Micheliolide (45). Attempts were made to deoxygenate this position by hydrogenolysis of the mesylate 53, with NaBH3CN/HMPA. However, the formation of the dienes 54 and 55 was verified. Also, the deoxygenation of this position by photolysis of the acetate 57 was unsuccessfully attempted. Finally, hydrogenation of 50 (Pd-C 10%, 5 psi, 15 minutes) led to a mixture of 52 and 58 (3:1) which, after separation, were transformed into 45 and 59, through elimination of methyl alcohol (NaOH/DMF)