text: The development of orthogonal protecting groups is a problem in organic synthesis because these protecting groups allow each instance of a common functional group, such as the hydroxyl group, to be distinguished during the synthesis of a complex molecule. A very common protecting group for the hydroxyl functional group is the para-methoxy benzyl (PMB) ether. This protecting group is chemically similar to the less electron-rich benzyl ether. Typically, selective cleavage of a PMB ether in the presence of a benzyl ether uses strong stoichiometric oxidants such as 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) or ceric ammonium nitrate (CAN). PMB ethers are far more susceptible to oxidation than benzyl ethers since they are more electron-rich. The selective deprotection of PMB ethers can be achieved through the use of bis-(2-(2,4-difluorophenyl)-5-trifluoromethylpyridine)-(4,4'-ditertbutylbipyridine)iridium(III) hexafluorophosphate (Ir[dF(CF)ppy](dtbbpy)PF) and a mild stoichiometric oxidant such as bromotrichloromethane, BrCCl. The photoexcited iridium catalyst is reducing enough to fragment the bromotrichloromethane to form a trichloromethyl radical, bromide anion, and the Ir(IV) complex. The electron-poor fluorinated ligands makes the iridium complex oxidising enough to accept an electron from an electron-rich arene such as a PMB ether. After the arene is oxidized, it will readily participate in hydrogen atom transfer with trichloromethyl radical to form chloroform and an oxocarbenium ion, which is readily hydrolyzed to reveal the free hydroxide. This reaction was demonstrated to be orthogonal to many common protecting groups when a base was added to neutralise the HBr produced.