Synthesis of mono- and di-potassium salts and methoxy adducts of sulfur-bridged biphenols by selective deprotonation

Abstract

Treatment of the sulfur-bridged biphenol [1,1′-S(2-HOC₆H₂Bu^t-3-Me-5)₂] with potassium hydride in diethyl ether results in the selective deprotonation of one phenol group to yield [1,1′-S(2-KO)(2′-HO)(C₆H₂Bu^t-3-Me-5)₂(Et₂O)], whereas an excess of potassium hydride in thf is required to generate the dianion [1,1′-S(2-KOC₆H₂Bu^t-3-Me-5)₂(thf)₂]; the same selective deprotonation is observed for the binaphthol [1,1′-S(2-HOC₁₀H₄Bu^t₂-3,6)₂], suggesting that intramolecular H-bonding stabilises the second, remaining hydroxyl group, allowing new, simple routes to tuneable, mono- or di-anionic aryloxide-based ligands.