Palladium-catalyzed oxidation of monoterpenes: novel tandem oxidative coupling-oxidation of camphene by dioxygen

The Pd-catalyzed stereoselective oxidative coupling of (-)-camphene gives m ainly (E,E)-diene, i.e., bis(3,3-dimethyl-2-norbornylidene)ethane, which ca n be oxidized into the corresponding alpha,beta -unsaturated ketone, i.e. ( 3,3-dimethyl-2-norbornyl) (8-camphenyl)ketone, with LiNO3 being used as a r eoxidant and dioxygen as a final oxidant; these two reactions are performed in a one port process with up to 90% selectivity for ketone. The applicati ons of the Pd(II)/NO3- catalytic system to the oxidation of limonene and be ta -pinene have also been studied. (C) 2001 Elsevier Science B.V. All right s reserved.