The oxidation of alcohols
to aldehydes, ketones and carboxylic acids is among the most important and
widely used class of oxidation reactions in organic chemical synthesis. Whereas
aerobic oxidation methods have been studied extensively, their use in
mainstream organic chemistry has been constrained by limitations in their
synthetic scope and by practical factors, such as the use of pure O2
as the oxidant or complex catalyst synthesis. This presentation will describe
the development of improved copper/TEMPO catalyst systems that enable
efficient and selective aerobic oxidation of a broad range of primary alcohols,
including allylic, benzylic and aliphatic derivatives, to the corresponding
aldehydes. The reactions often proceed at room temperature with ambient air as
the oxidant, and the catalyst system is compatible with a wide range of
functional groups and exhibits very high selectivity for primary alcohols.
Mechanistic studies provide key insights into the redox synergy between the
homogeneous copper and TEMPO cocatalysts.