Synthetic methods: part (ii) oxidation and reduction methods

This Report highlights advances in some of the most commonly used oxidation and reduction reactions, focusing on the literature from 2009. The review is subdivided in a similar fashion to the author's previous review in this area.1 In the field of oxidation, salen complexes, oxaziridinium salts and carbohydrate-derived dioxiranes continue to attract much attention in the context of alkene epoxidation. Elsewhere, a significant disclosure from Que is the first system able to catalyse the dearomatising dihydroxylation of an arene and Katsuki has reported the use of a dimeric Fe salan (reduced salen) complex to catalyse oxidative dimerisation of naphthols, affording BINOLs that are themselves ligands for asymmetric synthesis. In the field of reduction, the development of novel chiral phosphine ligands remains a prominent subject of research for alkene hydrogenation. There is sustained interest in oxazaborolidines as catalysts for ketone reduction and several methods for direct asymmetric reductive alkylation are reported. A general trend seen is increased activity in the area of green chemistry and there have been many reports on the use of nanoparticles as catalysts.