Iron(III)picolinate-catalyzed oxygenation of cholesteryl acetate with hydrogen peroxide or peracetic acid

Article abstract of DOI:10.1248/cpb.47.64

The reaction of cholesteryl acetate 1 with a Fe(III)(PA; picolinate)₃/H₂O₂/MeCN system (reagent system A), a simple model system for mono-oxygenases, gave mainly the 7α-hydroxylation product 2a, along with 7-ketonization product 3 and the 5,6-epoxidation product 4. On the other hand, reaction of 1 using a Fe(PA)₃/peracetic acid (AcOOH)/MeCN system (reagent system c) or a Fe(III)(ClO₄)₃ · 9H₂O-picolinic acid(PAH)- pyridine(Py)/AcOOH/MeCN system (reagent system F), provided 4 predominantly without formation of 2a. The former reaction may proceed via the dimeric Fe(III)-Fe(V) manifold complex, (PAH)(PA)₂Fe(III)-O-O-Fe(V)=O(PA)₂ (VII) as a hypothetically active species and a nonradical pathway, and the latter may proceed through monomeric iron complexes, [(PAH)(PA)₂Fe(V)=O]⁺ (IX) and [(PAH)(PA)₂Fe(V)(OH)(OOH)I⁺ (X).

Full text of DOI:10.1248/cpb.47.64

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