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Synlett 2008(16): 2540-2546  
DOI: 10.1055/s-2008-1078214
LETTER
© Georg Thieme Verlag Stuttgart ˙ New York

Iron/Copper-Cocatalyzed Ullmann N,O-Arylation Using FeCl3, CuO, and rac-1,1′-Binaphthyl-2,2′-diol

Zhe Wanga, Hua Fu*a, Yuyang Jianga,b, Yufen Zhaoa
a Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology (Ministry of Education), Department of Chemistry, Tsinghua University, Beijing 100084, P. R. of China
Fax: +86(10)62781695; e-Mail: fuhua@mail.tsinghua.edu.cn;
b Key Laboratory of Chemical Biology, College of Shenzhen, Tsinghua University, Guangdong Province, Shenzhen 518057, P. R. of China
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Publication History

Received 22 May 2008
Publication Date:
22 August 2008 (online)

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Abstract

We have developed an efficient and inexpensive bimetallic catalyst FeCl3, CuO, and rac-BINOL that could promote N,O-arylation of aliphatic, arylamines, and phenols. The cross-coupling reaction conditions have high tolerance of various functional groups. This versatile and efficient iron/copper-cocatalyst can widely be used in the synthesis of the compounds containing ­(aryl)C-N or (aryl)C-O(aryl) bond.

Key words

copper - iron - cross-coupling - N-arylation - O-arylation

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General Procedure A: Coupling of Aryl Halides with Amines A flask was charged with FeCl3 (16 mg, 0.1 mmol), CuO (8 mg, 0.1 mmol), Cs2CO3 (651 mg, 2 mmol), BINOL (57 mg, 0.2 mmol), and any remaining solids (amine and/or aryl halide). The flask was evacuated and backfilled with nitrogen (this procedure was repeated five times). Aryl halide (1 mmol, if liquid), amine (1.2 mmol, if liquid), and DMF (2 mL) were added to the flask under nitrogen atmosphere. The mixture was allowed to stir under nitrogen atmosphere at the shown temperature for the indicated period of time in the text (see Tables  [¹] and  [²] ). After cooling to r.t., the mixture was diluted with CH2Cl2 (ca. 20 mL), the solution was filtered, and the filter cake was further washed with CH2Cl2 (ca. 5 mL). The filtrate was washed with 1 M NaOH (ca. 10 mL). The combined aqueous phase was extracted with CH2Cl2 (2 × 10 mL). Organic layers were combined and dried over anhyd Na2SO4. The solvent of the filtrate was removed with the aid of a rotary evaporator, and the residue was purified by column chromatography on SiO2 using PE-EtOAc (60:1 to 10:1) as eluent to provide the desired product.
1-Phenyl-1H-indole (5l):¹6a yellow oil, yield 88%. ¹H NMR (300 MHz, CDCl3): δ = 7.61 (d, 1 H, J = 7.56 Hz), 7.42-7.51 (m, 5 H), 7.25-7.30 (m, 2 H), 7.13 (dd, 2 H, J = 9.60, 1.74 Hz), 6.61 (t, 1 H, J = 3.45 Hz). ¹³C NMR (75 MHz, CDCl3): δ = 139.9, 135.9, 129.7, 129.4, 128.1, 126.5, 124.5, 122.5, 121.2, 120.5, 110.6, 103.7. MS (EI): m/z = 193.23 [M+].

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General Procedure B: Coupling of Aryl Halides with Phenols A flask was charged with FeCl3 (16 mg, 0.1 mmol), CuO (8 mg, 0.1 mmol), Cs2CO3 (651 mg, 2 mmol), 1,1′-binaphthyl-2,2′-diol (57 mg, 0.2 mmol), and any remaining solids (phenol and/or aryl halide). The flask was evacuated and backfilled with nitrogen (this procedure was repeated five times). Aryl halide (1 mmol, if liquid), phenol (1.2 mmol, if liquid), and DMF (2 mL) were added to the flask under nitrogen atmosphere. The flask mixture was allowed to stir under nitrogen atmosphere at the shown temperature for the indicated period of time in the text (see Table  [³] ). After cooling to r.t., the mixture was diluted with CH2Cl2 (ca. 20 mL), the solution was filtered, and the filter cake was further washed with CH2Cl2 (ca. 5 mL). The solvent of the filtrate was removed with the aid of a rotary evaporator, and the residue was purified by column chromatography on SiO2 using PE or PE-EtOAc (60:1 to 100:1) as eluent to provide the desired product.
1-(4-Chlorophenoxy)-3-methylbenzene (7f):6d colorless oil, yield 79%. ¹H NMR (300 MHz, CDCl3): δ = 7.25 (dd, 2 H, J = 6.87, 2.07 Hz), 7.18 (d, 1 H, J = 7.53 Hz), 6.91 (dd, 3 H, J = 6.84, 2.04 Hz), 6.78 (s, 2 H), 2.31 (s, 3 H). ¹³C NMR (75 MHz, CDCl3): δ = 157.0, 156.2, 140.2, 129.8, 129.7, 128.2, 124.6, 120.1, 119.8, 116.1, 21.5. MS (EI): m/z = 218.22 [M+].