ACCEPTED MANUSCRIPT
HRMS (EI) calc. for [C8 H7 NOS]: 165.0248, found:
165.0250 ; MP 70 ºC.
4.2.10. 6-Bromobenzothiazole
(3j)
white
solid
(62%). 1 H NMR (400 MHz, CDCl3 ) δ 8.89 (s, 1H),
8.03 (d, J = 1.7 Hz, 1H), 7.92 (d, J = 8.7 Hz, 1H),
7.57
CDCl3 ) δ 154.45, 152.29, 135.59, 129.89, 124.87,
124.57, 119.50 ppm. HRMS (EI) calc. for
[C7 H4 BrNS]: 212.9248, found: 212.9248 ; MP 55 ºC.
4.2.3. 6-Ethoxybenzothiazole (3c) yellow oil (84%).
1 H NMR (400 MHz, CDCl3 ) δ 8.80 (s, 1H), 7.99 (d,
J = 8.9 Hz, 1H), 7.36 (d, J = 1.8 Hz, 1H), 7.10 (dd,
J = 8.9, 2.0 Hz, 1H), 4.08 (q, J = 7.0 Hz, 2H), 1.45
(t, J = 7.0 Hz, 3H) ppm. 1 3 C NMR (100 MHz, CDCl3 )
δ 157.47, 151.38, 147.87, 135.18, 124.07, 116.33,
104.81, 64.21, 14.92 ppm. HRMS (EI) calc. for
[C9 H9 NOS]: 179.0405, found: 179.0403
–
7.53 (m, 1H) ppm. 1 3 C NMR (100 MHz,
4.2.11. 6-Iodobenzothiazole (3k) white solid (66%).
1 H NMR (400 MHz, CDCl3 ) δ 8.91 (s, 1H), 8.30 (d,
J = 0.9 Hz, 1H), 7.87 (d, J = 8.6 Hz, 1H), 7.80 (dd,
J = 8.6, 1.1 Hz, 1H) ppm. 1 3 C NMR (100 MHz,
CDCl3 ) δ 154.41, 152.79, 136.03, 135.45, 130.56,
125.23, 90.31 ppm. HRMS (EI) calc. for [C7 H4 INS]:
260.9109, found: 260.9107 ; MP 81 ºC.
4.2.4. 6-Methylbenzothiazole (3d) yellow oil (63%).
1 H NMR (400 MHz, CDCl3 ) δ 8.83 (s, 1H), 7.94 (d,
J = 8.3 Hz, 1H), 7.67 (s, 1H), 7.25 (d, J = 8.3 Hz,
1H), 2.43 (s, 3H) ppm. 1 3 C NMR (100 MHz, CDCl3 )
δ 152.97, 151.54, 135.82, 134.01, 127.96, 123.18,
121.66, 21.65 ppm. HRMS (EI) calc. for [C8 H7 NS]:
149.0299, found: 149.0302
4.2.12. 6-Trifluoromethoxybenzothiazole(3l)
colorless oil (73%). 1 H NMR (400 MHz, CDCl3 ) δ
9.03 (s, 1H), 8.14 (d, J = 8.9 Hz, 1H), 7.83 (s, 1H),
7.40 (d, J = 8.9 Hz, 1H) ppm. 1 3 C NMR (100 MHz,
CDCl3 ) δ 155.14, 151.88, 146.99 (d, J = 2.1 Hz),
134.78, 124.63, 120.65 (d, J = 257.8 Hz), 120.36,
114.49 (d, J = 0.5 Hz) ppm. HRMS (EI) calc. for
[C8 H4 F3 NOS]: 218.9966, found: 218.9963
4.2.5. 6-Ethylbenzothiazole (3e) pale yellow oil
(60%).1 H NMR (400 MHz, CDCl3 ) δ 8.91 (s, 1H),
8.04 (d, J = 8.4 Hz, 1H), 7.77 (s, 1H), 7.36 (d, J =
8.4 Hz, 1H), 2.80 (q, J = 7.6 Hz, 2H), 1.31 (t, J =
7.6 Hz, 3H) ppm. 1 3 C NMR (100 MHz, CDCl3 ) δ
153.08, 151.70, 142.24, 134.05, 126.92, 123.32,
120.46, 29.05, 15.97 ppm. HRMS (EI) calc. for
[C9 H9 NS]: 163.0456, found: 163.0456
4.2.13. 4-Methoxybenzothiazole (3m) white solid
(33%). 1 H NMR (400 MHz, CDCl3 ) δ 8.90 (s, 1H),
7.52 (d, J = 8.1 Hz, 1H), 7.38 (t, J = 8.0 Hz, 1H),
6.93 (d, J = 7.9 Hz, 1H), 4.06 (s, 3H) ppm. 1 3 C
NMR (100 MHz, CDCl3 ) δ 154.05, 152.43, 143.74,
135.65, 126.70, 113.87, 106.57, 56.11 ppm. HRMS
(EI) calc. for [C8 H7 NOS]: 165.0248, found:
165.0249 ; MP 104 ºC.
4.2.6. 6-Tert-butylbenzothiazole (3f) yellow oil
(34%). 1 H NMR (400 MHz, CDCl3 ) δ 8.93 (s, 1H),
8.06 (d, J = 8.7 Hz, 1H), 7.95 (s, 1H), 7.59 (dd, J =
8.6, 1.5 Hz, 1H), 1.41 (s, 9H) ppm. 1 3 C NMR (100
MHz, CDCl3 )
δ 153.40, 151.36, 149.20, 133.92,
124.61, 123.01, 117.96, 35.22, 31.71 ppm. HRMS
(EI) calc. for [C1 1 H1 3 NS]: 191.0769, found:
191.0766
4.2.14. 4-Methylbenzothiazole
(3n)
yellow
oil
(54%). 1 H NMR (400 MHz, CDCl3 ) δ 8.98 (s, 1H),
7.80 (d, J = 7.0 Hz, 1H), 7.37 – 7.31 (m, 2H), 2.80
(s, 3H) ppm. 1 3 C NMR (100 MHz, CDCl3 ) δ 152.86,
152.71, 133.72, 133.62, 126.81, 125.62, 119.45,
18.53 ppm. HRMS (EI) calc. for [C8 H7 NS]:
149.0299, found: 149.0297
4.2.7. 5,6-Dimethylbenzothiazole (3g) white solid
(53%). 1 H NMR (400 MHz, CDCl3 ) δ 8.87 (s, 1H),
7.90 (s, 1H), 7.70 (s, 1H), 2.42 (s, 3H), 2.40 (s, 3H)
ppm. 1 3 C NMR (100 MHz, CDCl3 ) δ 152.90, 152.22,
135.62, 135.23, 131.24, 123.77, 121.80, 20.36,
20.34 ppm. HRMS (EI) calc. for [C9 H9 NS]:
163.0456, found: 163.0454 ; MP 108 ºC.
4.3. Recycling test
A tube-type Schlenk flask was charged with 0.06 mmol of
poly(NHC) D precatalyst salt (12 mol%, 16.0 mg), 0.06 mmol of
1,8-diazabicyclo[5.4.0]undec-7-ene (12 mol%, 9 ꢀL), and 1 mL
of N-methyl-2-pyrrolidone. The solution was stirred under
nitrogen atmosphere at 60 ºC for 30 minutes. And, 2 mL of N-
methyl-2-pyrrolidone was added, followed by adding a balloon
charged with carbon dioxide gas. The solution was and stirred at
60 ºC for 30 minutes. Then, 2-aminobenzenethiol (0.5 mmol, 54
ꢀL), phenylsilane (1.5 mmol, 186 ꢀL) dissolved in 0.5 mL of N-
methylpyrrolidone was added to the mixture. After 18 hours,
mesitylene (0.5 mmol, 70 ꢀL) was added as an internal standard
to determine the yield of product by Gas chromatography. After
that, the precatalyst salt was regenerated by adding 0.20 mmol of
47% hydroiodic acid (25 mol%, 36 ꢀL). The solvent, product,
silane and base were eliminated under reduced pressure at the
same time. The precatalyst salt was precipitated by adding
methanol. The catalytic performance of poly(NHC) was well
maintained during the seven times of recycling with 84-93%
determined by gas chromatography (1st run, 91%; 2nd run, 84%;
4.2.8. 6-Fluorobenzothiazole
(3h)
white
solid
(62%). 1 H NMR (400 MHz, CDCl3 ) δ 8.88 (s, 1H),
8.01 (dd, J = 9.0, 4.8 Hz, 1H), 7.59 – 7.55 (m, 1H),
7.23
–
7.16 (m, 1H) ppm. 1 3 C NMR (100 MHz,
CDCl3 ) δ 160.89 (d, J = 246.1 Hz), 153.71 (d, J =
2.5 Hz), 150.07, 133.65 (d, J = 265.6 Hz), 124.70 (d,
J = 9.4 Hz), 115.18 (d, J = 25.0 Hz), 108.07 (d, J =
26.0 Hz) ppm. HRMS (EI) calc. for [C7 H4 FNS]:
153.0048, found: 153.0046 ; MP 58 ºC.
4.2.9. 6-Chlorobenzothiazole (3i) pale yellow solid
(72%). 1 H NMR (400 MHz, CDCl3 ) δ 8.98 (s, 1H),
8.04 (d, J = 8.7 Hz, 1H), 7.94 (d, J = 1.7 Hz, 1H),
7.48 (dd, J = 8.7, 2.0 Hz, 1H) ppm. 1 3 C NMR (100
MHz, CDCl3 )
δ 154.43, 151.97, 135.10, 131.81,
127.21, 124.50, 121.61 ppm. HRMS (EI) calc. for
[C7 H4 ClNS]: 168.9753, found: 168.9752; MP 42 ºC.