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Synlett 2008(17): 2667-2670  
DOI: 10.1055/s-0028-1083509
LETTER
© Georg Thieme Verlag Stuttgart ˙ New York

FeCl2-Catalyzed Aminobromination of Alkenes Using Amides or Sulfonamides and NBS as the Nitrogen and Bromine Sources

Zhe Wanga, Yongming Zhanga, 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 (Guangdong Province), Graduate School of Shenzhen, Tsinghua University, Shenzhen 518057, P. R. of China
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Publication History

Received 20 June 2008
Publication Date:
01 October 2008 (online)

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Abstract

We have developed a convenient and efficient iron-catalyzed aminobromination of the alkenes using inexpensive FeCl2 as the catalyst, amides/sulfonamides and NBS as the nitrogen and bromine sources, respectively, under mild conditions.

Key words

iron - alkene - aminobromination - amide - sulfonamide - NBS

1

These two authors contributed equally to this work.

15

General Experimental Procedure for Aminohalogena-tion of Alkenes
Solid NBS (1.1 mmol, 196 mg) was added to the flask charged with FeCl2 (0.1 mmol, 13 mg), alkene (1.2 mmol), and amide or sulfonamide (1 mmol) in EtOAc (2 mL). The solution was stirred at r.t. (25 ˚C) or 50 ˚C for about 6 h. The resulting solution was diluted with EtOAc (8 mL) and washed with H2O and brine. The organic phase was dried over anhyd Na2SO4 and concentrated under rotary evaporation, and the residue was purified by column chromatography on silica gel (EtOAc-PE, v/v, 20:1 to 4:1) to provide the pure aminohalogenation product.
(±)- trans -1-( p -Fluorobenzamido)-2-bromocyclopentane (3b)
Yellow oil, yield 84%. ¹H NMR (300 MHz, CDCl3): δ = 7.94-7.91 (m, 2 H), 7.09-7.04 (m, 2 H), 5.10 (t, 1 H, J = 5.9 Hz), 4.71 (t, 1 H, J = 7.2 Hz), 2.11-1.92 (m, 2 H), 1.74-1.45 (m, 4 H). ¹³C NMR (75 MHz, CDCl3): δ = 162.9, 130.5, 124.1, 115.3, 85.1, 72.0, 34.8, 34.0, 23.3. HRMS: m/z calcd for C12H13BrFNO [M+]: 285.0165; found: 285.0171.