Palladium-catalyzed Aerobic Oxidation of Unprotected Polyols

Palladium-catalyzed aerobic oxidation of unprotected polyols Werner Oberhauser and Lorenzo Bettucci Istituto di Chimica dei Composti Organometallici (ICCOM-CNR), Area di Ricerca, CNR di Firenze, via Madonna del Piano 10, 50019 Sesto Fiorentino, Italy. E-mail: werner.oberhauser@iccom.cnr.it The oxidation of alcohols to carbonyl compounds is an important functional group transformation in organic chemistry.[1] Most of the actually applied synthetic protocols use either stoichiometric amounts of organic oxidants or toxic metal-based catalysts.[2] An attractive alternative to these oxidation protocols are palladium-based catalysts that use oxygen or air as oxidizing reagent, that are inexpensive, readily available and yield either H2O and/or H2O2 as by-products of the oxidation reaction.[3] The most promising palladium-based catalytic system for the aerobic alcohol oxidation comprises palladium acetate in combination with either pyridine-based ligands[4] or the water-soluble bathophenanthroline ligand.[5] We present the synthesis of a series of Pd-pyridine complexes characterized by a different Pd-ligand ratio and their application in the chemoselective aerobic oxidation of unprotected polyols carried out in a solvent mixture of toluene and DMSO. Literature: [1] J.-E. Bäckvall, Modern Oxidation Methods 2004, Wiley-VCH. [2] J. B. Arterburn, Tetrahedron 2001, 57, 9765. [3] S. S. Stahl, Angew. Chem. Int. Ed. 2004, 43, 3400. [4] T. Nishimura, T. Onoue, K. Ohe, S. Uemura, J. Org. Chem. 1999, 64, 6750. [5] G.-J. ten Brink, I. W. C. E. Arends, R. A. Sheldon, Science 2000, 287, 1636.