Pd-Catalyzed aerobic oxidation of the sesquiterpene isolongifolene: A green and heterogeneous process

Abstract

The oxidation of the sesquiterpene isolongifolene, catalyzed by Pd/SiO2 prepared through a conventional sol–gel method, resulted mainly in isolongifolen-9-one (65% selectivity), a compound which occupies a prominent place in perfume industry. In addition to the product obtained from the allylic oxidation of isolongifolene, the formation of other oxygenated products with potential industrial application (both total yield of 94%) was also observed. The system can be used for oxidation of other sesquiterpene, valencene. In this case, it was possible to obtain oxygenated products with up to 66% yield. The reactions occurred under mild conditions in a green and heterogeneous oxidation catalytic system. Pd (II) was used as a solo catalyst in the absence of co-oxidants. The catalyst can be easily recovered and re-used maintaining activity and selectivity.