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Representative Experimental Procedure for the CuBr2/1ox-Cata-
lyzed Aerobic Condensation Reactions of Primary Amines with
N-Alkyl-o-aminoanilines: Equimolar amounts of n-octylamine 2n
(0.161 g, 1.25 mmol) and N-methyl-o-aminoaniline (3a; 0.157 g,
[21]
1.25 mmol) with reduced organocatalyst 1red
0.05 mmol,
(8.35 × 10–3 g,
4
mol-%) and copper(II) bromide (2.4 × 10–3 g,
0.01 mmol, 0.8 mol-%) were mixed in a 9:1 mixture of 2-propanol/
water (25 mL) in air. The reaction mixture was stirred at 60 °C for
6 h. Then an additional aliquot of 1red (4.2 × 10–3 g, 0.025 mmol,
2 mol-%) was introduced into the reaction mixture and the reaction
was continued for a further 18 h. The solvent was then removed by
evaporation under reduced pressure and the residue was purified
by column chromatography on silica gel (eluent: ethyl acetate/pe-
troleum ether, 50:50, v/v) to give 1,2-disubstituted benzimidazole
4na (0.173 g, 60 % yield).
[7]
Benzimidazole 4na: White solid (recrystallized from petroleum
ether); m.p. 40–44 °C. 1H NMR (300 MHz, CDCl3, 25 °C, TMS): δ =
0.86–0.89 (t, J = 6.7 Hz, 3 H, CH3), 1.28–1.42 (m, 8 H, CH2), 1.81–1.83
(m, 2 H, CH2), 2.77–2.81 (t, J = 7.7 Hz, 2 H, CH2), 3.60 (s, 3 H, N-CH3),
7.19–7.2 (m, 3 H, Ar), 7.69–7.71 (m, 1 H, Ar) ppm. 13C NMR (75 MHz,
CDCl3, 25 °C, TMS): δ = 14.1 (CH3), 22.7 (CH2), 27.5 (CH2), 27.7 (CH2),
29.1 (CH2), 29.5 (CH2), 29.6 (CH3), 31.7 (CH2), 108.8 (CH, Ar), 119.1
(CH, Ar), 121.6 (CH, Ar), 121.8 (CH, Ar), 135.7 (Cq), 142.5 (Cq), 155.4
(Cq) ppm. HRMS (ESI+): calcd. for C15H23N2 [M + H]+ 231.1861; found
231.1872.
[8]
Supporting Information (see footnote on the first page of this
article): Characterization data for known compounds for which the
NMR spectroscopic data are not reported, high-field 1H NMR and
1D proton-decoupled 13C NMR spectra for all compounds.
Acknowledgments
The authors would like to thank Dr M.-B. Fleury, Emeritus Profes-
sor at the Paris Descartes University, for fruitful discussions. The
authors also thank the Association pour le Développement de
la Recherche Appliquée à la Pharmacologie (ADRAPHARM) for
financial support.
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Keywords: Homogeneous catalysis · Cross-coupling ·
Oxidation · Nitrogen heterocycles · Amines
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