Download PDF
Synlett 2005(11): 1687-1690  
DOI: 10.1055/s-2005-871545
LETTER
© Georg Thieme Verlag Stuttgart · New York

Mono- or Dichalcogenation of Aryl Iodide with Sulfur or Selenium by Copper Catalyst and Aluminum

Nobukazu Taniguchi*
Department of Chemistry, Fukushima Medical University, Fukushima 960-1295, Japan
Fax: +81(24)5471369; e-Mail: taniguti@fmu.ac.jp ;
Further Information

Publication History

Received 6 April 2005
Publication Date:
14 June 2005 (online)

    Permissions and Reprints All articles of this category

Abstract

The copper-catalyzed mono- or dichalcogenation of aryl halide with sulfur or selenium can be carried out with the addition of aluminum. This method takes advantage of two properties of both the insertion of copper into the chalcogen-chalcogen bond and the reductive ability of aluminum. Furthermore, the addition of MgCl2 or Na2CO3 enables the selective synthesis of diaryl mono-chalcogenides or disulfides.

Key words

diaryl chalcogenide - aryl iodide - chalcogen - copper catalyst - aluminum

10

Typical procedure for the preparation of diaryl sulfide: To a mixture of S (10.6 mg, 0.3 mmol), CuI (5.7 mg, 0.03 mmol), aluminum powder (53-150 µm) (16.2 mg, 0.6 mmol), MgCl2 (14.3 mg, 0.15 mmol), bpy (4.6 mg, 0.03 mmol), and DMF (0.5 mL) was added 2-iodotoluene (1a) (65.4 mg, 0.3 mmol), and the mixture was stirred at 110 °C for 24 h. After the reaction mixture was diluted with Et2O, the solution was washed with H2O and saturated NaCl, and dried over anhydrous MgSO4. Chromatography on silica gel (hexane) gave di-2-tolyl sulfide (22.8 mg, 71%). 1H NMR (270 MHz, CDCl3): δ = 2.38 (s, 6 H), 7.04-7.25 (m, 8 H); 13C NMR (67 MHz, CDCl3): δ = 20.1, 126.7, 127.1, 130.4, 131.1, 134.3, 138.9; Anal. Calcd for C14H14S: C, 78.45; H, 6.58. Found: C, 78.71; H, 6.61. Di-2-tolyl selenide: 1H NMR (270 MHz, CDCl3): δ = 2.39 (s, 6 H), 7.02-7.07 (m, 2 H), 7.14-7.25 (m, 6 H); 13C NMR (67 MHz, CDCl3) δ = 22.2, 126.8, 127.5, 130.2, 132.7, 133.2, 139.8; Anal. Calcd for C14H14Se: C, 64.37; H, 5.40. Found: C, 64.21; H, 5.17.

11

Typical procedure for the preparation of diaryl disulfide: To a mixture of sulfur (10.6 mg, 0.3 mmol), CuI (8.5 mg, 0.045 mmol), aluminum powder (53-150 µm) (16.2 mg, 0.6 mmol), Na2CO3 (15.9 mg, 0.15 mmol), bpy (7.0 mg, 0.045 mmol), and DMF (0.5 mL) was added 2-iodotoluene (1a) (65.4 mg, 0.3 mmol), and the mixture was stirred at 110 °C for 24 h. The reaction mixture was diluted with Et2O, the solution was washed with H2O and saturated NaCl, and dried over anhydrous MgSO4. Chromatography on silica gel (hexane) gave bis(2-tolyl) disulfide (34.0 mg, 92%). 1H NMR (270 MHz, CDCl3): δ = 2.42 (s, 6 H), 7.10-7.15 (m, 6 H), 7.49-7.52 (m, 2 H); 13C NMR (67 MHz, CDCl3): δ = 20.0, 126.7, 127.3, 128.7, 130.3, 135.4, 137.4; Anal. Calcd for C14H14S2: C, 68.24; H, 5.73. Found: C, 68.19; H, 5.70.

12

It is considered that because the disulfide bond of bis(4-bromophenyl) disulfide is easy to cleave, the monosulfide was obtained selectivity. The reaction of this disulfide with 2-iodotoluene in the presence of Na2CO3 gave 4-bromo-phenyl 2-tolyl sulfide in 50% yield.

13

Selenium was recovered in 90-92% yields.

14

The reaction of CuI (100 mol%) with Se gave a green precipitate. The structure of this compound is now under investigation.

15

In the reaction using Cu(II)Se or Cu(II)2Se in the presence of Al and MgCl2: Cu(II)Se afforded 2a in 45% yield after 40 h, and Cu(I)2Se resulted in a 5% yield after 80 h.