Ligand- and Counterion-Assisted Phenol O-Arylation with TMP-Iodonium(III) Acetates
Kotaro Kikushima, Naoki Miyamoto, Kazuma Watanabe, Daichi Koseki, Yasuyuki Kita* and Toshifumi Dohi*
*College of Pharmaceutical Sciences, Ritsumeikan University, 1-1-1, Nojihigashi, Kusatsu Shiga 525-8577, Japan, Email: kitaph.ritsumei.ac.jp, td1203ph.ritsumei.ac.jp
K. Kikushima, N. Miyamoto, K. Watanabe, D. Koseki, Y. Kita, T. Dohi, Org. Lett., 2022, 24, 1924-1928.
DOI: 10.1021/acs.orglett.2c00294
Abstract
The high reactivity of trimethoxyphenyl (TMP)-iodonium(III) acetate for phenol O-arylation enables access to various diaryl ethers in high yields. The TMP ligand and acetate anion cooperatively enhance the electrophilic reactivity toward phenol oxygen atoms. Various functional groups, including aliphatic alcohol, boronic ester, and sterically hindered groups, were tolerated during O-arylation.
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proposed mechanism
General Procedure for O-Arylation of Phenols
Phenol (0.20 mmol) and Na2CO3 (0.30 mmol, 1.5 eq) were dissolved in dichloromethane (2.0 mL) and H2O (2.0 mL) in a screw-capped test tube. TMP-iodonium(III) acetate (0.24 mmol, 1.2 eq) was added to the reaction mixture, and then stirred at 40 °C for 18 h. The reaction was quenched with sat. NH4Cl aq., and the mixture was transferred to a separatory funnel. The organic layer was separated, and the residual aqueous layer was extracted with dichloromethane (3 × 15 mL). The combined organic fractions were dried over Na2SO4, and all volatiles were removed under vacuum. The residue was purified by flash column chromatography (SiO2) to yield the corresponding diaryl ether.
Key Words
ID: J54-Y2022