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Synlett 2009(14): 2277-2280  
DOI: 10.1055/s-0029-1217723
LETTER
© Georg Thieme Verlag Stuttgart ˙ New York

Synthesis of Diaryliodonium Triflates Using Environmentally Benign Oxidizing Agents

Eleanor A. Merritt, Joel Malmgren, Felix J. Klinke, Berit Olofsson*
Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, 106 91 Stockholm, Sweden
Fax: +46(8)154908; e-Mail: berit@organ.su.se;
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Publikationsverlauf

Received 20 May 2009
Publikationsdatum:
31. Juli 2009 (online)

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Abstract

A range of symmetric and unsymmetric diaryliodonium triflates have been prepared employing urea-hydrogen peroxide as the oxidizing agent. The use of aqueous hydrogen peroxide and catalytic systems with methylrhenium trioxide in the oxidation of ­iodoarenes has also been investigated.

Key words

hypervalent iodine - diaryliodonium salts - oxidation - arenes - green chemistry

17

Diphenyliodonium Triflate (1a): A stirred mixture of CH2Cl2 and TFE (2:1, 1 mL) was cooled to 0 ˚C and UHP (47 mg, 0.50 mmol) was added. Tf2O (168 µL, 1.00 mmol) was added dropwise to the suspension and the mixture was stirred for 30 min at 0 ˚C. Iodobenzene (28 µL, 0.25 mmol) was added, followed by benzene (45 µL, 0.50 mmol) and the solution was warmed to r.t., then heated at 40 ˚C for 3 h. The mixture was allowed to cool to r.t., evaporated in vacuo and the residue was purified by trituration with Et2O (3 × 2 mL), then dried in vacuo to afford the title compound (82 mg, 76%) as an off-white amorphous solid, spectroscopically identical with literature data.6
( p -Tolyl)(phenyl)iodonium Triflate (1h): Prepared according to the above procedure. The crude reaction mixture was allowed to cool to r.t., evaporated in vacuo and the residue was partitioned between CH2Cl2 (5 mL) and H2O (5 mL). The aqueous layer was further extracted with CH2Cl2 (5 mL) and the organic extracts were combined and evaporated in vacuo. The residue was purified by trituration with Et2O (3 × 2 mL) and dried in vacuo to afford the title compound (84 mg, 76%) as an off-white amorphous solid, spectroscopically identical with literature data.6