Regioselective Oxidative Coupling of Monohalogenated Phenols
Ratnadeep Bera1, Raja Kapanaiah1, Doron Pappo1
1Department of Chemistry, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel.
None:
An aerobic, ortho-ortho selective oxidative coupling of monohalogenated phenols mediated by hydroxo multicopper(II) clusters is reported. The reaction proceeds by mixing phenols bearing chloro, bromo, or iodo substituents at the ortho, meta, or para positions with either [Cu4(pmbma)4(μ3-OH)4](OTf)4 (pmbma = N-(2-pyridinylmethylene)benzenemethanamine) or [Cu2(tmeda)2(μ-OH)2(OTf)](OTf) (TMEDA = N,N,N',N'-tetramethylethylenediamine) clusters in 1,1,1,3,3,3-hexafluoropropan-2-ol (HFIP) under an air atmosphere at elevated temperatures. The scalable protocol enables, for the first time, direct access to 3,3'-, 4,4'-, and 5,5'-dihalo-2,2'-biphenols, providing entry to valuable synthetic intermediates for preparing complex biphenyl architectures.
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