A thiolate ligand on a cytochrome P-450 mimic permits the use of simple environmentally benign oxidants for biomimetic steroid hydroxylation in water.

Manganese porphyrin systems carrying cyclodextrin binding groups can regioselectively and stereoselectively hydroxylate bound steroid substrates, using iodosobenzene as oxidant, but hydrogen peroxide and other simple oxidants such as sodium hypochlorite are not effective in water. Thiol ligands were then added to the catalyst, both covalently attached and hydrophobically bound, and with these ligands hydrogen peroxide was now an effective oxidant.