Synthesis of 1,2-Dibromobenzenes
32.9 mmol) in anhydrous THF (66 mL) under Ar at –78 °C. LTMP
was prepared in anhydrous THF (70 mL) at 0 °C by deprotonation
of tetramethylpiperidine (11.1 mL, 66.0 mmol) with BuLi
(66.0 mmol) in hexane (41.2 mL). The mixture was stirred at –78 °C
for 2 h, hydrolyzed with water (20 mL) at –78 °C, and warmed to
25 °C. Saturated aqueous NH4Cl (300 mL) was added and the mix-
ture was extracted with Et2O (3ϫ200 mL). The combined organic
layers were dried with Na2SO4. After removal of the solvent under
reduced pressure the residue that contained intermediate 2-(3,4-di-
bromo-5-trimethylsilylphenyl)-1,1,1,3,3,3-hexamethyldisilazane
was dissolved in a mixture of THF (50 mL), MeOH (33 mL), and
1 n aqueous H2SO4 (32 mL). The reaction mixture was stirred at
25 °C for 2 h, made alkaline with saturated aqueous Na2CO3
(300 mL), and extracted with Et2O (3ϫ200 mL). The combined
organic layers were dried with Na2SO4 and the solvents were re-
moved under reduced pressure. Purification of the crude by column
chromatography (cyclohexane/EtOAc, 8:2) afforded aniline 7c as a
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1
colorless oil (9.03 g, 85%). H NMR (300 MHz, CDCl3): δ = 0.37
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[s, 9 H, Si(CH3)3], 3.77 (br. s, 2 H, NH2), 6.69 (d, J = 2.7 Hz, 1 H,
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(C), 144.6 (C), 145.9 (C) ppm. HRMS (EI+): calcd. for
C9H1379Br2NSi [M]+ 320.9184; found 320.9191; calcd. for
C9H1379Br81BrNSi [M]+ 322.9164; found 322.9168.
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(4,5-Dibromobiphenyl-3-yl)trimethylsilane (7d): Prepared analo-
gously to silane 7a starting from 3,4-dibromobiphenyl (4a; 1.87 g,
6.00 mmol). Crystallization from MeOH at –20 °C afforded silane
7d as a colorless solid (1.59 g, 69%); m.p. 84–86 °C. 1H NMR
(300 MHz, CDCl3): δ = 0.45 [s, 9 H, Si(CH3)3], 7.36–7.48 (m, 3 H,
Ar-H), 7.52–7.55 (m, 3 H, Ar-H), 7.84 (d, J = 2.2 Hz, 1 H, Ar-
H) ppm. 13C NMR (75 MHz, CDCl3): δ = –0.20 (3 CH3), 126.9
(C), 127.2 (2 CH), 128.1 (CH), 129.1 (2 CH), 130.6 (C), 133.2 (CH),
133.5 (CH), 139.3 (C), 141.2 (C), 145.0 (C) ppm. HRMS (EI+):
calcd. for C15H1679Br2Si [M]+ 381.9388; found 381.9402; calcd. for
C15H1679Br81BrSi [M]+ 383.9368; found 383.9374.
[6]
[7]
[8]
[9]
{2,3-Dibromo-5-[methoxy(phenyl)methyl]phenyl}trimethylsilane (7e):
Prepared analogously to silane 7a starting from 4-[methoxy(phenyl)
methyl]-1,2-dibromobenzene (4h; 1.53 g, 4.29 mmol). Purification
of the crude by column chromatography (cyclohexane/CH2Cl2, 9:1)
afforded silane 7e as a colorless oil (1.39 g, 76%). 1H NMR
(300 MHz, CDCl3): δ = 0.36 [s, 9 H, Si(CH3)3], 3.37 (s, 3 H, OCH3),
5.15 (s, 1 H, CH-OMe), 7.28–7.38 (m, 6 H, Ar-H), 7.61 (d, J =
2.0 Hz, 1 H, Ar-H) ppm. 13C NMR (75 MHz, CDCl3): δ = –0.3 (3
CH3), 57.3 (CH3), 84.5 (CH), 126.6 (C), 127.0 (2 CH), 128.1 (CH),
128.8 (2 CH), 130.6 (C), 132.9 (CH), 133.2 (CH), 141.1 (C), 142.3
(C), 144.7 (C) ppm. HRMS (EI+): calcd. for C17H2079Br2OSi [M]+
425.9650; found 425.9648; calcd. for C17H2079Br81BrOSi [M]+
427.9630; found 427.9641; calcd. for C17H2081Br2OSi [M]+
429.9609; found 429.9662.
[10]
[11]
Supporting Information (see also the footnote on the first page of
1
this article): H, 13C, and 19F NMR spectra.
[12]
[13]
[14]
Acknowledgments
We are grateful to the Centre National de la Recherche Scientifique
(CNRS), the Ministère de l’Education Nationale et de la Recher-
che, and the Agence Nationale pour la Recherche (ANR program
07-BLAN-0292-01, MetChirPhos) for their financial support and a
postdoctoral grant to V. D. The authors thank Patrick Wehrung
for his precious help in HRMS analysis.
[15]
[16]
Eur. J. Org. Chem. 2011, 327–340
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
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