Microwave-assisted fast cyclohexane oxygenation catalyzed by iron-substituted polyoxotungstates

Under microwave irradiation, iron-substituted polyoxotungstates (Fe-POMs) catalyze cyclohexane oxygenation to A/K oil with 90-95% selectivity, unmatched turnover frequencies (40-400 h(-1)), and multi-turnover regime (> 1000 TON). Such a rapid reaction protocol allowed the screening of so-called inorganic Fe-synzymes with 1-4 nuclearity, including a family of Krebs-type isostructural complexes. Product distribution, kinetic analysis, mechanistic probes and fitting calculations, are consistent with a radical chain oxidation propagated by Fe-catalysed decomposition of organic peroxides which ultimately depends on the redox-properties and structural arrangement of the iron moiety within the POM cage.