A convenient TBHP/Cu(NO3)2·2.5H2O-mediated oxidation of secondary and benzyl alcohols under microwave irradiation

A microwave-assisted and solvent-free protocol for secondary and benzyl alcohols oxidation to the corresponding ketones and aldehydes, using the inexpensive and widely available Cu(NO₃)₂·2.5H₂O salt as catalyst and aqueous tert-butyl hydroperoxide (TBHP) as oxidant, has been developed. The present strategy allows the isolation of the oxidation products with yields up to 80% for the majority of the tested substrates. Extremely short reaction times and the usage of low-power microwave irradiation are factors that contribute to the smoothness of the process and are shown as an asset of the described experiment. Remarkably, the approach features a one-pot procedure, an earth-abundant copper catalyst, a wide substrate scope (22 alcohols) and a high compatibility with several functional groups.

Graphical abstract

As an ecological, widely available and economical material, the copper salt Cu(NO3)2∙2.5H2O show a high performance as catalyst in the oxidation of a series of secondary and benzyl alcohols. The developed protocol, using TBHP as oxidant and assisted by microwave radiation, proceeds without the use of an organic solvent and is very chemoselective tolerating the presence of several functional groups.