The effect of catalyst loading in copper-catalyzed cyclohexane functionalization by carbene insertion

A study of the variables that affect the insertion of the :CHCO2Et group (formed from ethyl diazocetate, EDA) into the C-H bonds of cyclohexane in the presence of a Tp(x)Cu complex as the catalyst (Tp(x) = trispyrazolylborate ligand) has demonstrated an anomalous effect of the catalyst loading. The use of low concentrations of catalyst produces an increase in the yield of the C-H activation product ethyl cyclohexaneacetate. This effect has also been found in the case of other less elaborated catalysts such as [Bp(Br3)Cu] or [(bipy)(2)Cu][I]. (c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007.