Copper catalyzed aromatization of conjugated and skipped dienes

Abstract

This research aims to develop a new and efficient catalytic system for aromatization of conjugated and skipped dienes. A system consisting of CuCl2 as a catalyst coupled with tert-butylhydroperoxide as an oxidant. Various parameters including type of ligands, solvent, temperature and reaction time display significant effects on the efficiency of the reaction. Skipped dienes such as -terpinene and 9,10-dihydroanthracene could be aromatized in high yields at room temperature in 5 minutes. On the other hand, conjugated dienes such as α-terpinene, 9,10-dihydrophenanthrene and 1,2-dihydronaphthalene needed more severe conditions or longer reaction time to produce high yield of their corresponding aromatized products. In addition, CuCl2-TBHP also gave moderate yield of aromatized product of heterocyclic such as indoline. Further application of this catalytic system could be utilize for aromatization of zingiberene to its corrresponding product, curcumene which possessed many bioactivities.