The oxygenation of cyclohexane under GifIV conditions – The catalytic behaviour of iron complexes

The catalytic oxygenation of cyclohexane to cyclohexanol (-ol) and cyclohexanone (-one) using a series of di- and trivalent iron-picolinate complexes under GifIV conditions (10:1 v/v pyridine–acetic acid, zinc powder at room temperature under aerobic atmosphere) proceeds with turnover numbers [defined as (moles of oxygenated products)/(moles of catalyst)] of 161–184 and -one:-ol ratios of 4.2–4.7. The corresponding values for the binuclear picolinate complex [Fe2(μ-OMe)2(pic)4] (237 turnovers, -one:-ol ratio 7.2) are significantly higher. Iron complexes bearing functionalised pyridyl ligands exhibit turnover numbers and ketone selectivities of similar magnitude to, and in some cases higher than, the picolinate complexes.

Graphical abstractGifIV catalysis using iron complexes with a range of nitrogen and oxygen donor sets has been investigated.Figure optionsDownload full-size imageDownload as PowerPoint slide