Synthese funktionalisierter hydroazulene - ein neuer zugang zum lactaran-gerüst

An efficient synthesis of hydroazulenes with the lactarane skeleton from the furan 1 is described. An efficient regioselective and stereoselective approach to the hydroazulenic skeleton of the lactarane sesquiterpenes is described. The furan 1 is transformed to the key intermediate 4. Regioselective intramolecular aldol reaction of 4 leads to the hydroazulenone 5 in excellent yield. Catalytic hydrogenation, followed by Wittig reaction, gives the compound 8, which is converted to the trimethylhydroazulenes 9 and 10 with five and seven stereogenic centers, respectively.