Change of Selectivity in C–H Functionalization Promoted by Nonheme Iron(IV)-oxo Complexes by the Effect of the N-hydroxyphthalimide HAT Mediator

[Image: see text] A kinetic analysis of the hydrogen atom transfer (HAT) reactions from a series of organic compounds to the iron(IV)-oxo complex [(N4Py)Fe(IV)(O)](2+) and to the phthalimide N-oxyl radical (PINO) has been carried out. The results indicate that a higher activating effect of α-heteroatoms toward the HAT from C–H bonds is observed with the more electrophilic PINO radical. When the N-hydroxy precursor of PINO, N-hydroxyphthalimide (NHPI), is used as a HAT mediator in the oxidation promoted by [(N4Py)Fe(IV)(O)](2+), significant differences in terms of selectivity have been found. Product studies of the competitive oxidations of primary and secondary aliphatic alcohols (1-decanol, cyclopentanol, and cyclohexanol) with alkylaromatics (ethylbenzene and diphenylmethane) demonstrated that it is possible to modify the selectivity of the oxidations promoted by [(N4Py)Fe(IV)(O)](2+) in the presence of NHPI. In fact, alkylaromatic substrates are more reactive in the absence of the mediator while alcohols are preferably oxidized in the presence of NHPI.