Aliphatic hydroxylation catalyzed by iron(III) porphyrins

Article abstract of DOI:10.1021/ja00030a028

Hydroxylation of aliphatic hydrocarbons with oxidants such as iodosobenzene can be effectively catalyzed with highly halogenated iron(III) porphyrins such as iron(III) tetrakis(2,6-dichlorophenyl)octabromoporphyrin. Hydroxylation of norbornane and tetraexodeuterionorbornane using this catalyst afforded good yields of products which consisted of 86:13:<1 and 84:16:<1 ratios of exo-norbornan-2-ol, endo-norbornan-2-ol, and 2-norbornanone, respectively. In the latter case both D₃ and D₄ exo and endo alcohols but only D₃ ketone were obtained. The primary isotope effect is 5. These results show that the reaction involves loss of stereochemistry and has a large isotope effect; the results are in agreement with those from a previous study of the same compounds using the enzyme cytochrome P-450. As in that case, this hydroxylation proceeds through a free-radical cage process. The hemin catalysis leads to a loss of stereospecificity similar to that in the enzyme-catalyzed reaction.