Lability of the trifluoromethyl group of trifluoromethoxybenzenes under HF/Lewis acid conditions

The trifluoromethyl functionality of trifluoromethoxybenzenes (trifluoromethyl phenyl ethers) becomes labile under HF/Lewis acid conditions. Substrates with an unsubstituted para-position shed their –CF3 groups while performing a Friedel–Crafts reaction upon another substrate moleculeʹs trifluoromethoxy group to generate p-rosolic acids. Substrates that had blocking groups at the para-positions reacted ortho. The electron donating substituents methoxy and phenoxy interfered with the formation of rosolic acids.