L. Yang et al.
Dyes and Pigments 187 (2021) 109079
ArH), 7.36 (dd, J = 7.6 Hz, 0.8 Hz, 1H, ArH), 7.27-7.26 (m, 1H, ArH),
7.13-7.10 (m, 2H, ArH), 4.26 (dd, J = 5.6 Hz, 1.6 Hz, 2H, CH2), 1.75-
1.69 (m, 1H, CH), 1.48-1.28 (m, 8H, CH2), 0.97-0.92 (m, 6H, CH3).
125.6, 121.3, 121.1, 119.2, 112.3, 104.5, 40.2, 38.6, 32.0, 29.5, 29.4,
27.8, 27.2, 24.9, 24.5, 22.8, 14.2, 12.5. Anal. calcd for C70H78N2O2S2: C,
80.57; H, 7.53; N, 2.68; S, 6.15. Found: C, 79.92; H, 7.55; N, 2.90; S,
6.19.
2.3.8. 2-Ethylhexyl-4,6-bis(5-bromothiophen-2-yl)-3-fluorothieno[3,4-b]
thiophene-2-carboxylate (8) [32]
Az-TT (0.20 g, 77%): M.p. 165–166 ◦C. 1H NMR (400 MHz, CDCl3,
ppm) δ 8.20 (s, 2H, ArH), 7.53 (s, 1H, ArH), 7.52 (s, 2H, ArH), 7.45 (s,
2H, ArH), 7.36 (d, J = 10.4 Hz, 2H, ArH), 7.31 (t, J = 4.0 Hz, 1H, ArH),
7.04 (d, J = 10.4 Hz, 2H, ArH), 4.29 (t, J = 5.6 Hz, 2H, CH2), 3.14-3.04
(m, 2H, CH), 2.84 (t, J = 4.0 Hz, 12H, CH3), 1.78-1.72 (m, 1H, CH), 1.51-
1.46 (m, 2H, CH2), 1.39 (d, J = 6.8 Hz, 12H, CH3), 1.45-1.31 (m, 6H,
CH2), 1.00-0.93 (m, 6H, CH3). 13C NMR (100 MHz, CDCl3, ppm) δ 161.6,
152.0, 149.1, 143.9, 143.8, 142.9, 141.6, 141.5, 139.02, 138.98, 138.4,
137.07, 137.04, 135.0, 134.44, 134.36, 134.3, 133.2, 133.1, 130.65,
130.56, 129.9, 129.7, 128.4, 128.3, 127.8, 127.5, 126.4, 125.1, 123.0,
121.1, 120.9, 112.15, 112.08, 68.2, 38.9, 38.6, 30.5, 29.1, 24.9, 24.5,
24.0, 23.1, 14.3, 12.5, 11.2. Anal. calcd for C53H55FO2S4: C, 73.06; H,
6.36; S, 14.72. Found: C, 73.55; H, 6.47; S, 15.82.
7 (0.95 g, 2.00 mmol) was dissolved in DMF (10 mL). The mixture
was stirred for 30 min in ice bath. Then a solution of NBS (0.78 g, 4.39
mmol) in DMF (20 mL) was added dropwise. The mixture was reacted at
room temperature for 2 h. When the reaction solution was poured into
water, the orange-red solid was precipitated, and filtered, recrystallized
to afford 8 (0.66 g, 50%). 1H NMR (400 MHz, CDCl3, ppm) δ 7.14 (dd, J
= 4.0 Hz, 0.8 Hz, 1H, ArH), 7.06 (dd, J = 3.6 Hz, 1.6 Hz, 2H, ArH), 6.98
(d, J = 4.0 Hz, 1H, ArH), 4.26 (dd, J = 5.6 Hz, 1.2 Hz, 2H, CH2), 1.74-
1.68 (m, 1H, CH), 1.49-1.33 (m, 8H, CH2), 0.97-0.90 (m, 6H, CH3).
2.3.9. Procedure for the synthesis of target compounds
PdCl2 (200 mg, 1.12 mmol) and triphenylphosphine (1.48 g, 5.60
mmol) were added to degassed dimethyl sulfoxide (DMSO, 32 mL) under
anhydrous condition in the dark, and the mixture was heated at 140 ◦C.
When the reaction solution changed from a turbid solution to an orange-
yellow clear one, the reaction mixture was cooled slightly and hydrazine
hydrate (0.4 mL) was injected with a syringe in the dark to precipitate
pale yellow solid. The reaction mixture was cooled to room temperature,
filtered, washed with ethanol and diethyl ether at Ar atmosphere under
anhydrous and dark conditions to afford Pd(pph3)4 (1.12 g, 86%).
1 or 2 (2.4 eq.), corresponding bromine 6, 8, 9 or 10 (1 eq.), Pd
(pph3)4 (6% eq.), and sodium carbonate (120 eq.) were added to a mixed
solvent (toluene:ethanol:water = 1:1:1.5, v/v/v) at Ar atmosphere. The
reaction mixture was heated at 90 ◦C for 12 h in the dark. The reaction
mixture was poured into water, extracted with ethyl acetate or
dichloromethane, washed with water, dried with anhydrous sodium
sulfate and filtered. The filtrate was concentrated under reduced pres-
sure and the residue was purified by silica gel column chromatography
or recrystallization to obtain the target compound.
Na-BT (0.32 g, 81%): M.p. 138–139 ◦C. 1H NMR (400 MHz, CDCl3,
ppm) δ 8.57 (d, J = 4.0 Hz, 2H, ArH), 8.18 (s, 2H, ArH), 7.90-7.84 (m,
8H, ArH), 7.58 (d, J = 4.0 Hz, 2H, ArH), 7.53-7.46 (m, 4H, ArH), 4.22 (t,
J = 7.2 Hz, 4H, CH2), 2.06-1.99 (m, 4H, CH2), 1.58-1.50 (m, 5H, CH2),
1.43-1.27 (m, 15H, CH2), 0.86 (t, J = 6.8 Hz, 6H, CH3). 13C NMR (100
MHz, CDCl3, ppm) δ 152.0, 151.0, 145.7, 134.1, 133.8, 133.0, 132.1,
131.9, 128.7, 128.2, 127.9, 126.7, 126.1, 124.4, 124.3, 123.6, 117.6,
74.7, 32.0, 30.7, 29.8, 29.5, 26.3, 22.8, 14.2. Anal. calcd for
C
50H52N2O2S3: C, 74.22; H, 6.48; N, 3.46; S, 11.89. Found: C, 74.35; H,
6.48; N, 3.58; S 12.6.
Na-DPP (0.22 g, 58%): M.p. > 280 ◦C, 1H NMR and 13C NMR spectra
were not characterized due to its very poor solubility. Anal. calcd for
C
50H52N2O2S2: C, 77.28; H, 6.75; N, 3.60; S, 8.25. Found: C, 75.59; H,
6.65; N, 3.83; S, 8.47.
Na-IID (0.29 g, 65%): M.p. 253–254 ◦C, 1H NMR (400 MHz, CDCl3,
ppm) δ 9.19 (d, J = 8.4 Hz, 2H, ArH), 8.08 (s, 2H, ArH), 7.87-7.76 (m,
8H, ArH), 7.52-7.39 (m, 8H, ArH), 7.33 (d, J = 8.4 Hz, 2H, ArH), 6.97 (s,
2H, ArH), 3.84 (t, J = 6.8 Hz, 4H, CH2), 1.80-1.72 (m, 4H, CH2), 1.50-
1.22 (m, 20H, CH2), 0.88 (t, J = 6.8 Hz, 6H, CH3). 13C NMR spectrum
was not characterized due to its poor solubility. Anal. calcd for
C60H58N2O2S2: C, 79.78; H, 6.47; N, 3.10; S, 7.10. Found: C, 78.93; H,
6.46; N, 3.32; S, 7.27.
Az-BT (0.52 g, 79%): M.p. 107–110 ◦C. 1H NMR (400 MHz, CDCl3,
ppm) δ 8.69 (d, J = 4.0 Hz, 2H, ArH), 8.23 (d, J = 1.6 Hz, 2H, ArH), 7.69
(d, J = 4.0 Hz, 2H, ArH), 7.36 (dd, J = 10.8 Hz, 1.6 Hz, 2H, ArH), 7.26 (s,
2H, ArH), 7.05 (d, J = 10.8 Hz, 2H, ArH), 4.24 (t, J = 7.2 Hz, 4H, CH2),
3.16-3.06 (m, 2H, CH), 2.92 (s, 6H, CH3), 2.87 (s, 6H, CH3), 2.10-2.03
(m, 4H, CH2), 1.58-1.51 (m, 4H, CH2), 1.40 (d, J = 7.2 Hz, 12H, CH3),
1.37-1.23 (m, 16H, CH2), 0.87 (t, J = 6.8 Hz, 6H, CH3). 13C NMR (100
MHz, CDCl3, ppm) δ 151.9, 151.1, 143.5, 142.8, 141.5, 140.1, 138.4,
137.0, 135.3, 134.2, 133.0, 132.0, 126.7, 126.3, 121.1, 117.7, 112.5,
74.7, 38.6, 32.0, 30.7, 29.8, 29.5, 26.2, 24.9, 24.4, 22.8, 14.2, 12.6.
Anal. calcd for C60H72N2O2S3: C, 75.90; H, 7.64; N, 2.95; S, 10.13.
Found: C, 75.49; H, 7.69; N, 3.12; S, 10.24.
Na-TT (0.29 g, 81%): M.p. 181–182 ◦C. 1H NMR (400 MHz, CDCl3,
ppm) δ 8.01 (s, 2H, ArH), 7.83-7.80 (m, 6H, ArH), 7.70 (d, J = 8.4 Hz,
2H, ArH), 7.49-7.36 (m, 7H, ArH), 7.17 (s, 1H, ArH), 4.25 (d, J = 6.0 Hz,
2H, CH2), 1.77-1.71 (m, 1H, CH), 1.50-1.35 (m, 8H, CH2), 0.99 (t, J =
7.6 Hz, 3H, CH3), 0.97 (t, J = 7.2 Hz, 3H, CH3). 13C NMR (100 MHz,
CDCl3, ppm) δ 161.5, 149.1, 145.9, 144.5, 134.0, 133.7, 133.2, 133.05,
133.97, 131.0, 130.6, 130.5, 129.1, 128.8, 128.5, 128.23, 128.19,
127.9, 126.8, 126.4, 126.3, 125.2, 124.8, 124.4, 124.3, 124.1, 123.9,
123.8, 117.1, 68.3, 38.9, 30.6, 29.1, 24.0, 23.2, 14.3, 11.2. Anal. calcd
for C43H35FO2S4: C, 70.65; H, 4.83; S, 17.54. Found: C, 68.72; H, 5.54; S
12.33.
Az-DPP (0.17 g, 48%): M.p. 268–269 ◦C. 1H NMR (400 MHz, CDCl3,
ppm) δ 9.15 (d, J = 4.4 Hz, 2H, ArH), 8.23 (d, J = 1.6 Hz, 2H, ArH), 7.70
(d, J = 4.0 Hz, 2H, ArH), 7.50 (s, 2H, ArH), 7.38 (dd, J = 10.4 Hz, 1.6 Hz,
2H, ArH), 7.06 (d, J = 10.8 Hz, 2H, ArH), 4.20 (t, J = 7.6 Hz, 4H, CH2),
3.15-3.04 (m, 2H, CH), 2.86 (s, 6H, CH3), 2.85 (s, 6H, CH3), 1.89-1.82
(m, 4H, CH2), 1.54-1.47 (m, 4H, CH2), 1.38 (d, J = 6.8 Hz, 12H, CH3),
1.34-1.25 (m, 16H, CH2), 0.86 (t, J = 6.8 Hz, 6H, CH3). 13C NMR
spectrum was not characterized due to its poor solubility. Anal. calcd for
C60H72N2O2S2: C, 78.56; H, 7.91; N, 3.05; S, 6.99. Found: C, 78.25; H,
7.95; N, 3.33; S, 7.09.
3. Results and discussion
3.1. Synthesis and characterization
The synthetic routes of target compounds are outlined in Scheme 2.
Guaiazulene borate (1) was synthesized by introduction of a boryl group
into the 2-position of the guaiazulene skeleton through the direct C–H
activation method with chloro(1,5-cyclooctadiene)iridium(I) dimer
catalysis [29]. After heated at 80 ◦C for 20 h, about 45% of guaiazulene
remained unreacted, which is consistent with the reported result [29].
Naphthalene borate (2) was synthesized by Miyaura boronation reaction
of 2-bromo naphthalene with bis(pinacolato)diboron in a yield of 49%
[30]. All target compounds were obtained by Suzuki coupling reaction
of guaiazulene borate (1) or naphthalene borate (2) with the corre-
sponding brominated intermediates (6, 8, 9, 10) in yields of 45% ~
Az-IID (0.23 g, 45%): M.p. 214–216 ◦C. 1H NMR (400 MHz, CDCl3,
ppm) δ 9.19 (d, J = 8.4 Hz, 2H, ArH), 8.20 (d, J = 1.2 Hz, 2H, ArH), 7.51
(dd, J = 7.6 Hz, 3.6 Hz, 4H, ArH), 7.37-7.34 (m, 4H, ArH), 7.04 (d, J =
10.8 Hz, 2H, ArH), 6.99 (d, J = 1.2 Hz, 2H, ArH), 3.84 (t, J = 7.2 Hz, 4H,
CH2), 3.15-3.04 (m, 2H, CH), 2.85 (s, 6H, CH3), 2.84 (s, 6H, CH3), 1.80-
1.73 (m, 4H, CH2), 1.49-1.42 (m, 4H, CH2), 1.39 (d, J = 7.2 Hz, 12H,
CH3), 1.36-1.22 (m, 16H, CH2), 0.87 (t, J = 7.2 Hz, 6H, CH3). 13C NMR
(100 MHz, CDCl3, ppm) δ 168.4, 145.4, 144.4, 143.9, 142.3, 141.6,
139.5, 138.4, 137.8, 137.1, 134.5, 133.3, 131.8, 130.5, 127.8, 126.4,
5