Radical-Cation Catalysis in the Synthesis of Diphenylmethanes via the Dealkylative Coupling of Benzylic Ethers

Article abstract of DOI:10.1021/jo00128a020

The dealkylative coupling of benzyl alkyl ethers (ArCH2OR) to yield the corresponding diarylmethanes (ArCH2Ar) together with dialkoxymethane (ROCH2OR) is catalyzed by small amounts of 1-electron oxidants (such as aromatic cation radicals, NO(1+), etc.) or by an equivalent electrochemical (anodic) method.The catalytic method is successfully employed for the facile synthesis of a novel macrocyclic crown ether 18 that contains a diarylmethane linkage.On the basis of the spectral observation of the radical cation ArCH2OR^.+ and the excellent catalytic efficiency with turnover numbers in excess of 1E2, an electron-transfer and an alternative electrophilic chain mechanism are discussed for the dealkylative coupling process.