SYNTHESIS OF 2-THIOPHENECARBOXYLIC
473
(ë5), 162.80 (ë=é), 51.23 (éëç3), 15.46 (ëç3). Mass 133.36 (ë2), 134.76 (ë3), 138.05 (ë4), 127.70 (ë5),
spectrum, m/z (Irel, %): 156 [M+] (51), 39 (5), 45 (24), 161.98 (ë=é), 65.80 (éëç2), 21.77 (ëç2), 15.42
53 (22), 69 (7), 70 (8), 85 (7), 96 (10), 97 (15), 124 (20), (ëç3), 10.12 (ëç3). Found, %: C 58.59; H 6.45; S
125 (100), 126 (10), 122 (7), 141 (12). Found, %: C 17.29. Calculated for C9H12O2S, %: C 58.63; H 6.56; S
53.71; H 5.13; S 20.45. Calculated for C7H8O2S, %: C 17.39.
53.82; H 5.16; S 20.52.
Methyl 5-acetyl-2-thiophenecarboxylate (5a).
Yield, 85%; bp 127–128°C/1 Pa. 13C NMR (CDCl3, δ,
ppm): 139.36 (ë2), 133.40 (ë3), 131.58 (ë4), 148.43
(ë5), 161.95 (ë=é), 52.18 (éëç3), 190.50 (ë=é),
26.87 (ëç3). Mass spectrum, m/z (Irel, %): 156 [M+]
(40), 39 (5), 45 (12), 57 (24), 69 (5), 97 (10), 125 (100),
126 (12), 127 (5), 155 (5). Found, %: C 53.79; H 5.11;
S 20.57. Calculated for C7H8O3S, %: C 53.82; H 5.16;
S 20.52.
Methyl 5-chloro-2-thiophenecarboxylate (7a).
Yield, 65%; bp 87–88°C/5 Pa. 13C NMR (CDCl3, δ,
ppm): 132.01 (ë2), 133.13 (ë3), 127.17 (ë4), 137.64
(ë5), 161.46 (ë=é), 52.21 (éëç3). Mass spectrum,
m/z (Irel, %): 176 [M+] (43), 37 (5), 38 (7), 45 (5), 53 (5),
57 (7), 59 (4), 69 (4), 73 (24), 75 (7), 81 (7), 82 (9), 117
(12), 118 (5), 119 (7), 144 (5), 145 (100), 146 (12), 147
(41), 175 (5). Found, %: C 40.73; H 2.81; Cl 19.98; S
18.09. Calculated for C6H5ClO2S, %: C 40.80; H 2.85;
Cl 20.07; S 18.15. Literature data: bp 95–97°C/7 Pa
[17].
Methyl 5-bromo-2-thiophenecarboxylate (8a).
Yield, 77%;mp 87–88°C. 13C NMR (CDCl3, δ, ppm):
134.64 (ë2), 133.61 (ë3), 130.61 (ë4), 120.17 (ë5), 161.46
(ë=é), 52.21 (éëç3). Mass spectrum, m/z (Irel, %): 221
[M+] (12), 37 (10), 38 (17), 45 (10), 53 (4), 57 (10), 59
(5), 69 (5), 76 (14), 77 (33), 117 (10), 119 (9), 141 (4),
161 (10), 163 (10), 188 (9), 189 (98), 190 (19), 191
(100), 192 (10), 193 (7), 219 (10), 220 (45). Found, %:
C 32.41; H 2.25; Br 36.17; S 14.35. Calculated for
C6H5BrO2S, % C 32.59; H 2.28; Br 36.14; S 14.47.
Methyl 5-iodo-2-thiophenecarboxylate (9a).
Yield, 24%; mp 88°C. 13C NMR (CDCl3, δ, ppm):
139.32 (ë2), 134.18 (ë3), 137.69 (ë4), 81.99 (ë5),
161.24 (ë=é), 52.15 (ëç3). Found, %: C 26.75; H
1.79; I 47.24; S 11.87. Calculated for C6H5IO2S, %: C
26.88; H 1.88; I 47.34; S 11.96. Literature data: mp 88–
89°C [20].
Methyl 4-methyl-2-thiophenecarboxylate (4b).
Yield, 41%; bp 84–85°C/2 Pa. 13C NMR (CDCl3, δ,
ppm): 133.82 (ë2), 135.32 (ë3), 138.09 (ë4), 128.21
(ë5), 162.28 (ë=é), 52.02 (éëç3), 15.08 (ëç2). Mass
spectrum, m/z (Irel, %): 156 [M+] (46), 39 (5), 45 (24),
51 (5), 53 (24), 69 (7), 70 (6), 85 (7), 96 (7), 97 (14),
124 (20), 125 (100), 126 (10), 127 (5), 141 (12). Found,
%: C 53.77; H 5.08; S 20.55. Calculated for C7H8O2S,
%: C 53.82; H 5.16; S 20.52.
Dimethyl 3-methyl-2,5-thiophenedicarboxylate
(4c). Yield, 25%; mp. 82–83°C. 13C NMR (CDCl3, δ,
ppm): 136.56 (ë2), 145.75 (ë3), 135.83 (ë4), 138.39
(ë5), 162.09 (C=O), 162.58 (C=O), 52.37 (éëç3),
51.95 (éëç3), 15.81 (ëç3). Mass spectrum, m/z (Irel,
%): 241 [M+] (40), 39 (5), 41 (3), 45 (10), 51 (5), 53 (5),
59 (11), 65 (5), 67 (60), 69 (7), 70 (7), 83 (5), 95 (7), 96
(9), 125 (5), 155 (7), 181 (5), 182 (14), 183 (100), 184
(12), 185 (6), 199 (14), 211 (5). Found, %: C 50.35; H
4.68; S 15.05. Calculated for C9H10O4S, %: C 50.45; H
4.70; S 14.96. Literature data: mp 84°C [12].
Ethyl 3-methyl-2-thiophenecarboxylate (4d).
Yield, 32%; bp 87°C/5 Pa. 13C NMR (CDCl3, δ, ppm):
126.43 (ë2), 147.49 (ë3), 131.60 (ë4), 129.84 (ë5),
162.89 (ë=é), 60.55 (ëç2), 14.22 (ëç3). Mass spec-
trum, m/z (Irel, %): 170 [M+] (20), 38 (5), 39 (7), 45 (30),
51 (7), 53 (40), 69 (8), 70 (7), 85(10), 96 (10), 97 (42),
98 (5), 124 (40), 125 (100), 126 (20), 141 (42), 142
(37), 169 (10). Found, %: C 56.29; H 5.85; S 18.83.
Calculated for C8H10O2S, %: C 56.44; H 5.92; S 18.35.
Literature data: bp 84°C/4 Pa [19].
Diethyl
3-methyl-2,5-thiophenedicarboxylate
(4e). Yield, 20%; bp 135–136°C/20 Pa. 13C NMR
(CDCl3, δ, ppm): 126.07 (ë2), 147.49 (ë3), 136.19 (ë4),
133.43 (ë5), 161.95 (ë=é), 60.49 (ëç2), 60.81 (ëç2),
18.80 (ëç3), 13.89 (ëç3), 15.39 (ë3-ëç3). Mass spec-
trum, m/z (Irel, %): 242 [M+] (40), 39 (10), 41 (3), 43 (5),
45 (50), 51 (6), 52 (5), 53 (60), 67 (9), 69 (13), 70 (14),
71 (5), 76 (5), 84 (6), 85 (10), 95 (8), 96 (9), 97 (11),
124 (4), 125 (10), 140 (4), 141 (6), 142 (7), 168 (50),
169 (100), 170 (20), 184 (21), 185 (40), 186 (32), 196
(45), 197 (55), 198 (25), 212 (10), 213 (21), 214 (22),
241 (24). Found, %: C 54.45; H 5.68; S 13.21. Calcu-
lated for C11H14O4S, %: C 54.52; H 5.82; S 13.23.
Ethyl 5-chloro-2-thiophenecarboxylate (7b).
Yield, 30%; bp 95°C/1 Pa. 13C NMR (CDCl3, δ, ppm):
132.05 (ë2), 133.11 (ë3), 127.30 (ë4), 137.42 (ë5), 161.46
(ë=é), 61.17 (ëç2), 14.05 (ëç3). Found, %: C 44.18; H
3.62; Cl 18.43; S 16.74. Calculated for C7H7ClO2S, %:
C 44.09; H 3.70; Cl 18.598; S 16.82. Literature data: bp
75°C/0.3 Pa [14].
Propyl 3-methyl-2-thiophenecarboxylate (4f).
Yield, 24%; bp 92°C/4 Pa. 13C NMR (CDCl3, δ, ppm):
126.78 (ë2), 145.57 (ë3), 131.47 (ë4), 129.65 (ë5),
162.54 (ë=é), 66.09 (éëç2), 21.68 (ëç2), 15.36
(ëç3), 10.02 (ëç3). Found, %: C 58.52; H 6.44; S
17.31. Calculated for C9H12O2S, %: C 58.63; H 6.56; S
17.39.
Ethyl 5-bromo-2-thiophenecarboxylate (8b).
Yield, 55%; bp 120°C/1 Pa. 13C NMR (CDCl3, δ, ppm):
134.85 (ë2), 133.60 (ë3), 130.63 (ë4), 126.97 (ë5),
161.44 (ë=é), 60.49 (ëç2), 13.80 (ëç3). Found, %: C
35.64; H 2.89; Br 34.08; S 13.48. Calculated for
C7H7BrO2S, %: C 35.76; H 3.00; Br 33.99; S 13.64.
Propyl 5-bromo-2-thiophenecarboxylate (8c).
Propyl 4-methyl-2-thiophenecarboxylate (4g). Yield, 63%; bp 98°C/1 Pa. 13C NMR (CDCl3, δ, ppm):
Yield, 75%; bp 72°C/1 Pa. 13C NMR (CDCl3, δ, ppm): 133.49 (ë2), 132.84 (ë3), 130.89 (ë4), 120.04 (ë5),
PETROLEUM CHEMISTRY Vol. 48 No. 6 2008