Copper-Catalyzed Synthesis of Diaryl Selenide from Aryl Iodide and Diphenyl Diselenide Using Magnesium Metal

Abstract

Various unsymmetrical diaryl selenides can be synthesized from aryl iodides and diphenyl diselenide by an addition of magnesium metal in the presence of a copper catalyst. This method can exploit efficiently two phenylselenide-molecules generated from diphenyl diselenide under neutral conditions.

Key words

copper catalyst - magnesium - diaryl selenide - aryl iodide - diphenyl diselenide

References

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7

In the experiment of entry 1 in Tables [1] , 97% 2-iodotoluene and 89% diphenyl diselenide were recovered; no other products were obtained at all.

8

The magnesium metal could not reduce diphenyl diselenide under our conditions. In entry 2 in Tables [1] , 97% 2-iodotoluene and 96% diphenyl diselenide were recovered.

10

The reaction between CuI and (PhSe)₂ produced a green precipitate. The structure of this compound is now under investigation.

11

Cu(I)SePh could be prepared by refluxing Cu₂O and PhSeH in EtOH for 24 h.

14

A typical procedure is given for the reaction of 2-iodotoluene with diphenyl diselenide giving phenyl 2-tolyl selenide (entry 1 in Table [2] ): To a mixture of Cu₂O (2.1 mg, 0.015 mmol), magnesium(powder) (14.6 mg, 0.6 mmol), 2,2′-bipyridyl(bpy) (4.6 mg, 0.03 mmol) and DMF (0.5 mL) were added 2-iodotoluene (65.4 mg, 0.3 mmol) and diphenyl diselenide (46.8 mg, 0.15 mmol), and the mixture was stirred at 110 °C for 30 h. After evaporation of the solvent, the residue was dissolved in Et₂O. The solution was washed with H₂O and sat. NaCl and dried over anhyd MgSO₄. Chromatography on silica gel(hexane) gave phenyl 2-tolyl selenide (78.1 mg, 92%). ¹H NMR (270 MHz, CDCl₃): δ = 2.39 (s, 3 H), 7.06 (t, J = 7.0 Hz, 1 H), 7.15-7.41 (m, 7 H), 7.56-7.62 (m, 1 H). ¹³C NMR (67.5 MHz): δ = 22.3, 126.7, 127.1, 127.7, 127.8, 129.1, 129.3, 130.2, 131.5, 132.7, 133.6. ⁷⁷Se (51 MHz): δ = 479.7. 4-Bromophenyl phenyl selenide: ¹H NMR (270 MHz, CDCl₃): δ = 7.26-7.31 (m, 5 H), 7.35-7.38 (m, 2 H), 7.45-7.48 (m, 2 H). ¹³C NMR (67.5 MHz): δ = 121.4, 127.7, 129.4, 130.3, 132.3, 133.2, 133.3, 134.2. ⁷⁷Se (51 MHz): δ = 432.0. Anal. Calcd for C₁₂H₉SeBr: C, 46.19; H, 2.91. Found: C, 46.39; H, 3.05. Phenyl 4-trifluoromethylphenyl selenide: ¹H NMR (270 MHz, CDCl₃): δ = 7.24-7.37 (m, 3 H), 7.40-7.47 (m, 4 H), 7.55-7.58 (m, 2 H). ¹³C NMR (67.5 MHz): δ = 125.8, 125.8, 125.9, 126.0, 128.5, 128.7, 129.7, 131.0, 134.8. ⁷⁷Se (51 MHz): δ = 443.1. Anal. Calcd for C₁₃H₉F₃Se: C, 51.84; H, 3.01. Found: C, 51.69; H, 3.14.