Manganese(III) Porphyrin Catalysts for the Oxidation of Terpene Derivatives: A Comparative Study

A comparative study involving four manganese(III) porphyrin catalysts combined with two different oxidants (sodium hypochlorite and potassium monopersulfate) has been performed in the epoxidation of three terpene derivatives. The catalytic oxidation of α-pinene produces selectively 100% of the epoxide or 65% of allylic oxidation products, only by modification of the substituents on the meso-positions of the metalloporphyrin catalyst. The catalytic oxidation of the 5-vinyl-2-norbornene is regio- and stereoselective, producing only the exo-2,3-epoxy-5-vinylnorbornane. With α-terpinene, a conjugated di-olefin, an oxidative dehydrogenation reaction was surprisingly observed, producing p-cymene as a major compound.