HYPERVALENT IODINE-INDUCED NUCLEOPHILIC-SUBSTITUTION OF PARASUBSTITUTED PHENOL ETHERS - GENERATION OF CATION RADICALS AS REACTIVE INTERMEDIATES

A novel hypervalent iodine induced nucleophilic substitution of para-substituted phenol ethers in the presence of a variety of nucleophiles is described. UV and ESR spectroscopic studies indicate that this reaction proceeds via cation radicals, [ArH.+], as reactive intermediates generated by single-electron transfer (SET) from a charge-transfer (dT) complex of phenol ethers with phenyliodine(III) bis(trifluoroacetate) (PIFA). This is the first case that involves a radical intermediate on hypervalent iodine oxidations of aromatic compounds.