The biomimetic oxidation of etodolac, an anti-inflammatory drug (1) with iodosylbenzene catalyzed by 5,10,15,20-tetraarylporphyrinatoiron(III) chlorides TAPFe(III)Cl (7a-e) in dichloromethane gives 4-hydroxyetodolac (6) and 4-oxoetodolac (5) regioselectively in moderate yields.Key words etodolac; halogenated and perhalogenated metalloporphyrin; iodosylbenzene; 4-hydroxyetodolac; 4-oxoetodolac Etodolac, 1,3,4,-indole-1-acetic acid (1) is a clinically effective antiinflammatory agent, possesses an exceptional safety profile with respect to the gastrointenstinal tract and renal function.1,2) The major primary oxidative metabolites of 1 in man are 6-hydroxyetodolac (2), 7-hydroxyetodolac (3), and 8-(1Ј-hydroxy)etodolac (4), whereas the major metabolite in rat is 4-oxoetodolac (5). The biomimetic oxidation of selected drugs with monooxygen donors catalyzed by 5,10,15,20-tetraarylporphyrinatoiron(III) chlorides (TAPFe(III)Cl) has been studied to understand the drug metabolism as well as to isolate the drug metabolites and reactive intermediates in sufficient amount without the use of experimental animals.3-6) The catalytic activity of metalloporphyrins can be increased either by introduction of bulkier substituents at ortho position of the phenyl rings or by substitution of hydrogens by halogens of main porphyrin ring of metalloporphyrins (TAPFe(III)Cl). Herein, we report the biomimetic oxidation of etodolac with iodosylbenzene catalyzed by halogenated and perhalogenated iron(III) porphyrins TAPFe(III)Cl (7a-e) 7) in organic solvents to mimic the reactions of natural cytochrome P450 enzyme.Iodosylbenzene (1 mmol, 220 mg) was added to a mixture of 1 (1 mmol, 287 mg) and Cl 8 TPPFe(III)Cl (7b) (0.01 mmol) in dichloromethane (10 ml). The reaction mixture was stirred for 2 h at room temperature. The solvent was removed under reduced pressure and the residue was chromatographed on silica gel. The elution of column with petrol : chloroform The reaction of 1 with iodosylbenzene catalyzed by TPPFe(III)Cl (7a) in dichloromethane in after 2 h gives regioselctively 6 in 11.3% and 5 in 5.0% yield (Chart 1).