Heteroaromatic ethers of phenols in nickel-catalysed ipso-replacement reactions with magnesium, zinc and tin organometallic compounds

Phenols are readily converted in high yield into the heterocyclic ethers, 5 -aryloxy-1-phenyl-1H-tetrazole, 1 and 3-aryloxy-1 lambda(6),2-benzothiazole 1,1-dioxide, 2. X-Ray crystallographic analysis and other evidence shows t hat, in these ethers, the originally strong phenolic C-OH bond is considera bly weakened on derivatization. In nickel-catalysed cross-coupling reaction s with organozinc and organotin compounds, the heterocyclic parts of ethers 1,2 provide good nucleofuges. In similar cross-coupling reactions with org anomagnesium halides, ethers 1 again provide good nucleofuges but, in marke d contrast, ethers 2 do not. In all reactions, palladium based catalysts we re mostly not effective.