Cu-Catalyzed Fluorination of Diaryliodonium Salts with KF

Abstract

A mild Cu-catalyzed nucleophilic fluorination of unsymmetrical diaryliodonium salts with KF is described. This protocol preferentially fluorinates less sterically hindered aromatic rings. The reaction exhibits a broad substrate scope and proceeds with high chemoselectivity and functional group tolerance. DFT calculations implicate a CuI/CuIII catalytic cycle.

The new breed of cutting-edge catalysts

“…Currently, the bonds are made using expensive specialized reagents or the highly corrosive gas hydrogen fluoride. In 2013, a team of researchers led by Sanford showed 9 how to make such bonds with a safer potassium fluoride salt using a copper catalyst. First, the catalyst is exposed to a compound that strips away three of its electrons.…”

Synthesis of fluorinated oxygen- and sulfur-containing heteroaromatics

“…Expanding on this work, Ichiishi et al have employed copper catalysts to selectively fluorinate the smaller aromatic ligand in unsymmetrical diaryliodonium salts [105]. The reaction shows broad substrate scope, including electron rich aromatic rings.…”

Activation and Formation of Aromatic C–F Bonds

“…16) [40]. In the presence of copper triflate, 18-crown-6, and potassium fluoride, diaryliodonium salts underwent fluorination at the more substituted arene.…”