10.1002/ejoc.201700165
European Journal of Organic Chemistry
FULL PAPER
7.18 (m, 1H, Hthioph), 2.57 ppm (s, 3H, CH3); 13C NMR (75 MHz, CDCl3,
300 K) δ = 144.6 (C), 135.4 (C), 134.8 (CH), 131.8 (CH), 128.4 (CH), 127.
(CH), 14.2 ppm (CH3); elemental analysis calcd (%) for C7H7NO2S: C
49.69, H 4.17, N 8.28; found: C 49.43, H 4.13, N 8.22.
(CH3); elemental analysis calcd (%) for C9H11NO2S: C 54.80, H 5.62, N
7.10; found: C 54.72, H 5.63, N 7.09.
(E)-2-bromo-5-(2-nitropropenyl)thiophene (1i).[27] Method A. Yellow
solid; 66% yield. 1H NMR (400 MHz, CDCl3, 300 K) δ = 8.18 (s, 1H,
Halkenyl), 7.20 (d, J = 4.0 Hz, 1H, Hthioph), 7.17 (d, J = 4.0 Hz, 1H, Hthioph),
2.51 ppm (s, 3H, CH3); 13C NMR (100 MHz, CDCl3, 300 K) δ = 144.7 (C),
136.8 (C), 135.0 (CH), 131.2 (CH), 126.7 (CH), 119.8 (C), 14.4 ppm
(CH3); elemental analysis calcd (%) for C7H6BrNO2: C 33.89, H 2.44, N
5.65; found: C 34.00, H 2.32, N 5.56.
(E)-2-(2-nitrobutenyl)thiophene (1b). Method B. Yellow oil; 69% yield.
1H NMR (300 MHz, CDCl3, 300 K) δ = 8.25 (s, 1H, Halkenyl), 7.64 (d, J =
5.1 Hz, 1H, Hthioph), 7.43 (d, J = 3.6 Hz, 1H, Hthioph), 7.19 (dd, J = 5.1, 3.6
Hz, 1H, Hthioph), 3.04 (q, J = 7.4 Hz, 2H, CH2), 1.28 ppm (t, J = 7.4 Hz, 3H,
CH3); 13C NMR (75 MHz, CDCl3, 300 K) δ = 150.3 (C), 135.3 (CH), 135.1
(C), 132.1 (CH), 128.6 (CH), 127.0 (CH), 21.8 (CH2), 12.0 ppm (CH3);
elemental analysis calcd (%) for C8H9NO2S: C 52.44, H 4.95, N 7.64;
found C 52.73, H 5.10, N 7.44.
(E)-2-(2-nitrobutenyl)-5-(phenylethynyl)thiophene (1j). Method A.
Yellow solid; 78% yield. 1H NMR (400 MHz, CDCl3, 300 K) δ = 8.19 (s,
1H, Halkenyl), 7.65 - 7.51 (m, 2H, Hphenyl), 7.41 (s, 3H, Hphenyl), 7.33 (d, J =
3.9 Hz, 1H, Hthioph), 7.31 (d, J = 3.9 Hz, 1H, Hthioph), 3.04 (q, J = 7.4 Hz,
2H, CH2), 1.31 ppm (t, J = 7.4 Hz, 3H, CH3); 13C NMR (100 MHz, CDCl3,
300 K) δ = 150.4 (C), 135.5 (C), 135.1 (CH), 132.4 (CH), 131.6 (CH),
129.9 (C), 129.2(CH), 128.5 (CH), 126.3 (CH), 122.1 (C), 97.3 (C), 81.9
(C), 21.6 (CH2), 11.7 ppm (CH3); elemental analysis calcd (%) for
C16H13NO2S: C 67.82, H 4.62, N 4.94; found: C 67.43, H 4.70; N, 4.86.
(E)-2-(2-nitro-3-phenylpropenyl)thiophene (1c). Method B. Yellow oil;
47% yield. 1H NMR (300 MHz, CDCl3, 300 K) δ = 8.51 (s, 1H, Halkenyl),
7.62 (d, J = 5.1 Hz, 1H, Hthioph), 7.49 (d, J = 3.5 Hz, 1H, Hthioph), 7.38 –
7.22 (m, 5H, Hphenyl), 7.19 (dd, J = 5.1, 3.5 Hz, 1H, Hthioph), 4.44 ppm (s,
2H, CH2); 13C NMR (75 MHz, CDCl3, 300 K) δ = 147.1 (C), 135.8 (CH),
135.7 (C), 134.9 (C), 132.4 (CH), 129.2 (CH), 129.0 (CH), 128.7 (CH),
128.3 (CH), 127.4 (CH), 33.8 ppm (CH2); elemental analysis calcd (%) for
C13H11NO2S: C 63.65, H 4.52, N 5.71; found C 64.02, H 4.72, N 5.60.
(E)-2-(2-nitropropenyl)benzo[b]thiophene (1k).[34] Method A. Yellow
solid; 82% yield; 1H NMR (400 MHz, CDCl3, 300 K) δ = 8.37 (s, 1H,
Halkenyl), 7.88 (d, J = 7.5 Hz, 2H, Hphenyl), 7.68 (s, 1H, Hthioph), 7.46 (dd, J =
7.5, 3.9 Hz, 2H, Hphenyl), 2.66 ppm (s, 3H, CH3); 13C NMR (100 MHz,
CDCl3, 300 K) δ = 146.2 (C), 142.0 (C), 138.6 (C), 134.9 (CH), 132.1 (C),
127.8 (CH), 126.7 (CH), 125.3 (CH), 124.8 (CH), 122.4 (CH), 14.3 ppm
(CH3); elemental analysis calcd (%) for C11H9NO2S: C 60.26, H 4.14, N
6.39; found: C 60.52, H 4.18, N 6.15.
(E)-2-(2-nitro-2-phenylvinyl)thiophene (1d).[32] Method E. Yellow solid;
85 % yield. 1H NMR (300 MHz, CDCl3, 300 K) δ = 8.51 (s, 1H, Halkenyl),
7.66 - 7.53 (m, 3H, Hphenyl), 7.43 - 7.40 (m, 2H, Hphenyl), 7.39 (d, J = 5.0
Hz, 1H, Hthioph), 7.34 (d, J = 3.6 Hz, 1H, Hthioph), 7.05 ppm (dd, J = 5.0, 3.5
Hz, 1H, Hthioph); 13C NMR (75 MHz, CDCl3, 300 K) δ = 146.8 (C), 136.2
(CH), 135.3 (C), 133.3 (CH), 131.1 (CH), 130.7 (CH), 129.9 (C), 129.7
(CH), 129.3 (CH), 127.7 ppm (CH); elemental analysis calcd (%) for
C12H9NO2S: C 62.32, H 3.92, N 6.06; found: C 62.31, H 3.86, N 6.08.
(E)-2-(2-nitrobutenyl)benzo[b]thiophene (1l). Method A. Yellow solid;
78% yield. 1H NMR (400 MHz, CDCl3, 300 K) δ = 8.31 (s, 1H, Halkenyl),
7.88 (d, J = 6.9 Hz, 2H, Hphenyl), 7.66 (s, 1H, Hthioph), 7.46 (t, J = 5.0 Hz,
2H, Hphenyl), 3.12 (q, J = 7.4 Hz, 2H, CH2), 1.34 ppm (t, J = 7.4 Hz, 3H,
CH3); 13C NMR (100 MHz, CDCl3, 300 K) δ = 151.7 (C), 142.0 (C), 138.5
(C), 134.5 (C), 132.2 (CH), 127.2 (CH), 126.7 (CH), 125.3 (CH), 124.7
(CH), 122.5 (CH), 21.6 (CH2), 12.3 ppm (CH3); elemental analysis calcd
(%) for C12H11NO2S: C 61.78, H 4.75, N 6.00; found: C 61.77, H 4.64, N
5.69.
(E)-2-(2-nitrovinyl)thiophene (1e).[29] Method D. Yellow solid; 57% yield.
1H NMR (300 MHz, CDCl3, 300 K) δ = 8.18 (d, J = 13.4 Hz, 1H, Halkenyl),
7.58 (d, J = 5.0 Hz, 1H, Hthioph), 7.50 (d, J = 13.4 Hz, 1H, Halkenyl), 7.48 (d,
J = 3.1 Hz, 1H, Hthioph), 7.21 - 7.13 ppm (m, 1H, H Thioph); 13C NMR (75
MHz, CDCl3, 300 K) δ = 135.5 (C), 134.7 (CH), 133.9 (CH), 132.2 (CH),
131.7 (CH), 129.0 ppm (CH); elemental analysis calcd (%) for
C6H5NO2S: C 46.44, H 3.25, N 9.03; found: C 46.25, H 3.02, N 8.84.
(E)-ethyl 2-nitro-3-(thiophenyl)acrylate (1f).[28] Method C. Yellow solid,
58% yield. 1H NMR (400 MHz, CDCl3, 300 K), δ = 7.73 (s, 1H, Halkenyl),
7.71 (d, J = 5.0 Hz, 1H, Hthioph), 7.49 ( d, J = 3.8 Hz, 1H, Hthioph), 7.18 (dd,
J = 5.0, 3.9 Hz, 1H, Hthioph), 4.39 (q, J = 7.2 Hz, 2H, CH2 ), 1.40 ppm (t, J
= 7.1 Hz, 3H, CH3 ). 13C NMR (100 MHz, CDCl3, 300 K) δ = 159.5 (C),
135.7 (CH), 134.3 (CH), 131.8 (C), 128.5 (CH), 126.7 (CH), 62.9 (CH2),
14.1 ppm (CH3); EI-MS (M = 227); elemental analysis calcd (%) for
C9H9NO4S: C 47.57, H 3.99, N 6.16; found: C 47.17, H 4.06, N 6.30.
(E)-3-(2-nitropropenyl)thiophene (1m).[35] Method A. Yellow solid; 72%
yield. 1H NMR (400 MHz, CDCl3, 300 K) δ = 8.09 (s, 1H, Halkenyl), 7.62 (d,
J = 2.5 Hz, 1H, Hthioph), 7.46 (dd, J = 5.1, 2.9 Hz, 1H, Hthioph), 7.30 (d, J =
5.1 Hz, 1H, Hthioph), 2.51 ppm (s, 3H, CH3); 13C NMR (100 MHz, CDCl3,
300 K) δ = 146.4 (C), 133.8 (C), 129.9 (CH), 128.2 (CH), 127.6 (CH),
127.0 (CH), 14.2 ppm (CH3); elemental analysis calcd (%) for C7H7NO2S:
C 49.69, H 4.17, N 8.28; found: C 49.94, H 4.14, N 8.20.
General
nitroalkenylthiophenes.
procedure
for
the
synthesis
of
α-substituted
(E)-2-methyl-5-(2-nitropropenyl)thiophene (1g).[33] Method A. Yellow
solid; 72% yield. 1H NMR (300 MHz, CDCl3, 300 K) δ = 8.22 (s, 1H,
Halkenyl), 7.26 (d, J = 3.3 Hz, 1H, Hthioph), 6.86 (d, J = 3.6 Hz, 1H, Hthioph),
2.58 (s, 3H, CH3), 2.52 ppm (s, 3H, CH3); 13C NMR (75 MHz, CDCl3, 300
K) δ = 148.2 (C), 143.4 (C), 136.1 (CH), 133.7 (C), 128.2 (CH), 127.2
(CH), 16.2 (CH3), 14.6 ppm (CH3); elemental analysis calcd (%) for
C8H9NO2S: C 52.44, H 4.95, N 7.64; found: C 52.54, H 4.90, N 7.56.
Mg turnings (370 mg, 15.2 mmol) were placed in a Schlenk flask and
heated under vacuum. After filling the flask with dinitrogen, THF (10 mL)
and a small crystal of iodine were added. Then 2-bromothiophene (2.0 g,
12.2 mmol) in THF (10 mL) was added dropwise to the mixture while
stirring at such a rate as to avoid the boiling of the solvent. After the
addition, the reaction mixture was stirred for
a further 3h. The
(E)-2-methyl-5-(2-nitrobutenyl)thiophene (1h). Method A. Yellow solid;
72% yield. 1H NMR (300 MHz, CDCl3, 300 K) δ = 8.15 (s, 1H, Halkenyl),
7.24 (d, J = 3.6 Hz, 1H, Hthioph.), 6.84 (d, J = 3.6 Hz, 1H, Hthioph), 2.97 (q, J
= 7.4 Hz, 2H, CH2), 2.56 (s, 3H, CH3), 1.24 ppm (t, J = 7.4 Hz, 3H, CH3);
13C NMR (75 MHz, CDCl3, 300 K) δ = 149.0 (C), 148.4 (C), 136.3 (CH),
133.1 (C), 127.7 (CH), 127.2 (CH), 21.7 (CH2), 16.1 (CH3), 12.0 ppm
organomagnesium reagent was filtered on a frit to remove excess Mg
and then added dropwise at RT to a solution of the nitrile (10.7 mmol) in
THF (5 mL). The solution was then heated at 60 °C for 4 h. Completion of
the reaction was check by TLC. The reaction was quenched with MeOH
(5 mL) and the solvent was evaporated in vacuo. The residue was taken
up with anhydrous, degassed CH2Cl2 (30 mL) and filtered over a small
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