Transition‐Metal‐Free Aryl–Aryl Cross‐Coupling: C−H Arylation of 2‐Naphthols with Diaryliodonium Salts

Abstract

Transition‐metal‐free regioselecitive C−H arylation of 2‐naphthols with diaryliodonium salts has been developed. The reaction proceeds under very simple experimental conditions and affords a range of products with various substitution patterns. The method allows for the incorporation of electron‐deficient aryls, which complements well currently existing metal‐free aryl–aryl cross‐couplings of phenols that have been so far restricted to the introduction of electron‐rich aryl moieties. The mechanism of the reaction was studied by means of DFT calculations, demonstrating that the C−C bond formation occurs via a dearomatization of 2‐naphthol substrate, followed by a subsequent rearomatization by tautomerization. The computations show that the use of a low polarity solvent and an insoluble inorganic base is key to securing the high selectivity of the C−C coupling over a competing C−O arylation pathway, by preventing the incipient deprotonation of 2‐naphthol.

Aryl‐Aryl Cross‐Coupling with Hypervalent Iodine Reagents: Aryl Group Transfer Reactions

“…Recently, in 2019 Kalek group [46] reported a transition metal‐free regioselective aryl‐aryl cross‐coupling reactions of 2‐naphthols with diaryliodonium salts. The symmetrical diaryliodonium salts with electron deficient functional groups was identified as potential aryl source (Scheme 41).…”

Copper-Catalyzed Synthesis of Axially Chiral Biaryls with Diaryliodonium Salts as Arylation Reagents

“…The progress in synthesis of biaryls employing diaryliodonium salts as aryl cation equivalents has made this class of bench-stable, nontoxic, and readily available reagents attract attention [ 35 , 36 , 37 , 38 , 39 ]. Moreover, copper catalyst can be oxidized in the presence of diaryliodonium salts to form a highly electrophilic aryl-Cu(III) intermediate and a range of latent nucleophiles undergo arylation reactions to form synthetically versatile products [ 39 , 40 ].…”

The Diaryliodonium(III) Salts Reaction With Free-Radicals Enables One-Pot Double Arylation of Naphthols

“…In this case, only few examples are known. Quideau (Ozanne-Beaudenon and Quideau, 2005), described C-and Oarylation mixtures and Kalek (Ghosh et al, 2019) reported on the selective C-arylation of naphthols using fluorinated Ar 2 IOTf. In all these protocols, the stoichiometric use of a base is needed for the reaction giving rise to the monoarylation of naphthols by transferring one aryl group from Ar 2 IX via an ionic pathway (Oh et al, 1999).…”