Beilstein J. Org. Chem. 2020, 16, 1066–1074.
tion under reduced pressure the crude product was obtained as a and dichlorobis(triphenylphosphine)palladium(II) (40 mg,
brown solid. After crystallisation of the crude product with 0.06 mmol) were dissolved in tetrahydrofuran (20 mL). The
chloroform, the pure product 2 (692 mg, 47%) was obtained as reaction mixture was refluxed for 24 h under an argon atmo-
white crystals. Rf (ethyl acetate/hexane, 1:6 v/v): 0.43; melting sphere. After removing the solvent, the crude product was dis-
point: 200–201°C; 1H NMR (600 MHz, CDCI3) δ (ppm) 8.19 solved in dichloromethane and washed with water (3 × 20 mL).
(d, J = 1.9 Hz, 1H), 8.08 (s, 1H), 8.02 (dd, J = 7.7, 1.1 Hz, 1H), The combined extracts were dried over sodium sulfate and then
7.50 (dd, J = 8.5, 1.9 Hz, 1H), 7.47–7.40 (m, 2H), 7.31 (d, J = filtered. Upon concentration under reduced pressure, the crude
8.6 Hz, 1H), 7.25 (td, J = 6.3, 1.8 Hz, 1H).
product was obtained as a dark green–yellow liquid. The crude
product was first purified by flash column chromatography (1:3
3-Bromo-9-hexylcarbazole (4): 4 was synthesised as reported CH2Cl2/hexane v/v) followed by preparative thin-layer chroma-
previously [33-35]. A mixture of 3-bromocarbazole (2, 1.5 g, tography (4:2:1 hexane/CHCI3/MeOH v/v/v). The pure product
6.0 mmol), 1-bromohexane (4.0 g, 24.3 mmol), tetrabutylam- 7a (176 mg, 63%) was obtained as a yellow liquid which solidi-
monium iodide (225 mg, 0.6 mmol) and aqueous sodium fied on standing. Rf (dichloromethane/hexane, 1:1 v/v): 0.3,
hydroxide (26 mL, 50%) was heated at 77 °C for 8 h. The prod- melting point: 91–93 °C, 1H NMR (600 MHz, CDCI3) δ (ppm)
uct was extracted with dichloromethane (3 × 20 mL), and the 10.17 (s, 1H), 8.95 (dd, J = 4.8, 0.9 Hz, 1H), 8.83 (d, J =
combined extracts were dried over sodium sulfate and then 1.8 Hz, 1H), 8.24 (s, 1H), 8.23–8.16 (m, 3H), 7.58 (dd, J = 4.9,
filtered. Upon concentration under reduced pressure, the crude 1.4 Hz, 1H), 7.53–7.46 (m, 3H), 7.44 (d, J = 8.0 Hz, 1H), 7.28
product was obtained as a light yellow liquid. The crude prod- (dt, J = 7.3, 0.8 Hz, 1H), 4.33 (t, J = 7.3 Hz, 3H), 1.90 (p, J =
uct was purified by flash column chromatography (2:98 triethyl- 7.7 Hz, 3H), 1.47–1.37 (m, 3H), 1.37–1.19 (m, 6H), 0.87 (t, J =
amine/hexane v/v). Pure compound 4 (1.7 g, 84%) was ob- 7.1 Hz, 4H); 13C NMR (600 MHz, CDCI3) δ (ppm) 192.0,
tained as a colourless liquid which solidified on standing. Rf 160.0, 150.9, 142.5, 141.5, 141.0, 129.1, 126.1, 124.8, 123.4,
(hexane): 0.3, melting point: 48–49 °C; 1H NMR (600 MHz, 123.1, 120.6, 119.4, 119.3, 119.3, 118.6, 109.0, 108.9, 43.3,
CDCI3) δ (ppm) 8.20 (d, J = 1.9 Hz, 1H), 8.04 (d, J = 7.8, 31.6, 29.0, 27.0, 22.5, 14.0; FTIR (cm−1): 2956, 2924, 2911,
1.1 Hz, 1H), 7.53 (dd, J = 8.6, 1.9 Hz, 1H), 7.48 (td, J = 8.3, 2872, 2851, 1697; anal. calcd for C24H24N2O, C: 80.87, H:
1.2 Hz, 1H), 7.40 (d, J = 8.2 Hz, 1H), 7.28 (d, J = 8.6 Hz, 1H), 6.79, N: 7.86; found: C: 80.86, H: 6.92, N: 7.57.
7.24 (t, 1H), 4.27 (t, J = 7.3 Hz, 3H), 1.85 (p, J = 7.4 Hz, 3H),
1.34–1.23 (m, 6H), 0.86 (t, J = 7.0 Hz, 4H).
Compound 7b: (9-Hexylcarbazol-3-yl)boronic acid pinacol
ester (5, 144 mg, 0.4 mmol), 2-bromopyridine-5-carbaldehyde
(9-Hexylcarbazole-3-yl)boronic acid pinacol ester (5): 5 was (6b, 47 mg, 0.3 mmol), potassium carbonate (1 M, 3 mL) and
synthesised as reported previously [36,37]. Bis(pinacol- dichlorobis(triphenylphosphine)palladium(II) (13 mg,
ato)diboron (423 mg, 1.7 mmol), potassium acetate (446 mg, 0.02 mmol) were dissolved in tetrahydrofuran (10 mL). The
4.5 mmol) and dichlorobis(triphenylphosphine)palladium(II) reaction mixture was refluxed for 6 h under an argon atmo-
(35 mg, 0.05 mmol) catalyst were added to a 3-bromo-N-hexyl- sphere. After removing the solvent, the crude product was dis-
carbazole (4, 500 mg, 1.5 mmol) solution in 1,4-dioxane solved in dichloromethane and washed with water (3 × 20 mL).
(15 mL). The reaction mixture was heated at 90 °C for 24 h The combined extracts were dried over sodium sulfate and then
under an argon atmosphere. The crude product was extracted filtered. Upon concentration under reduced pressure, the crude
with dichloromethane (3 × 20 mL), and the combined extracts product was obtained as a dark green-yellow liquid. The crude
were dried over sodium sulfate and then filtered. Upon concen- product was first purified by flash column chromatography
tration under reduced pressure, the crude product was obtained (dichloromethane/hexane, 1:1 v/v) followed by preparative thin-
as a brown–black liquid. The product was purified by flash layer chromatography (hexane/chloroform/MeOH, 10:5:2
column chromatography (CH2Cl2/hexane 1:4 v/v). Pure prod- v/v/v). The pure product 7b (67 mg, 75%) was obtained as a
uct 5 (404 mg, 71%) was obtained as a colourless liquid. Rf yellow solid. Rf (dichloromethane/hexane, 5:1 v/v): 0.3; melting
(CH2Cl2/hexane, 1:2 v/v): 0.32, 1H NMR (600 MHz, CDCI3) δ point: 89–91°C; 1H NMR (600 MHz, CDCI3) δ (ppm): 10.12 (s,
(ppm) 8.60 (s, 1H), 8.13 (d, J = 7.6 Hz, 1H), 7.91 (dd, J = 8.1, 1H), 9.13 (d, J = 2.2 Hz, 1H), 8.88 (d, J = 1.8 Hz, 1H),
2.5 Hz, 1H), 7.46 (t, J = 7.4 Hz, 1H), 7.42–7.36 (m, 2H), 7.23 8.26–8.17 (m, 3H), 8.01 (d, J = 8.3 Hz, 1H), 7.53–7.48 (m, 2H),
(d, J = 7.6 Hz, 1H), 4.30 (t, J = 7.0 Hz, 2H), 1.86 (t, J = 7.6 Hz, 7.44 (d, J = 8.1 Hz, 1H), 7.29 (t, J = 7.4 Hz, 1H), 4.34 (t, J =
2H), 1.49–1.15 (m, 18H), 0.85 (t, J = 7.1 Hz, 3H).
7.3 Hz, 3H), 1.90 (p, J = 7.4 Hz, 2H), 1.44–1.25 (m, 6H), 0.87
(t, J = 7.1 Hz, 3H); 13C NMR (600 MHz, CDCI3) δ (ppm)
Compound 7a: (9-Hexylcarbazol-3-yl)boronic acid pinacol 190.5, 163.1, 152.7, 142.0, 141.1, 136.2, 129.1, 128.8, 126.2,
ester (5, 447 mg, 1.2 mmol), 2-bromopyridine-4-carbaldehyde 125.3, 123.5, 123.1, 120.7, 120.1, 119.9, 119.5, 109.1, 109.1,
(6a, 147 mg, 0.8 mmol), potassium carbonate (1 M, 9.6 mL) 43.3, 31.5, 28.9, 26.9, 22.5, 14.0; FTIR (cm−1): 2950, 2924,
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