Facile and Selective Cross-Coupling of Phenols Using Selenium Dioxide

Nonsymmetric biphenols are important structural motifs in organic chemistry. Therefore, an easy and versatile protocol for oxidative cross‐coupling is essential to generate these so‐called “privileged ligands”. We developed an efficient and selective oxidative pathway to synthesize 2,2′‐biphenols as well as 2,4′‐ and 4,4′‐biphenols. The use of selenium dioxide, a stable, powerful, and commercially available oxidizer, in 1,1,1,3,3,3‐hexafluoroisopropanol allowed the oxidative coupling of alkyl‐, alkoxy‐, and halogen‐substituted phenols. With a little help from the solvent 1,1,1,3,3,3‐hexafluroisopropanol (HFIP) and the common oxidizer selenium dioxide, phenolic substrates are selectively converted into the respective mixed biphenols.