반응 #8801

반응 방정식

amide

3-nitrothiophene-2-carboxamide

Triethylamine

trifluoroacetic anhydride

→

2-cyano-3-nitrothiophene

수율 96.6%

용매

dichloromethane

반응 조건

후처리

1. 1
   온도to warm to room temperature
2. 2
   농축The solution was concentrated in vacuo
3. 3
   세척washed successively with hydrochloric acid (1N, 2×), water (1×), saturated aqueous sodium hydrogencarbonate (2×) and brine
4. 4
   건조Drying over sodium sulfate and removal of solvent
5. 5
   기타gave a dark solid, which
6. 6
   기타was purified by flash chromatography (400 g of silica gel, petroleum ether:ethyl acetate 7:3+1% MeOH as eluent)

실험 절차

The amide 30 (15.5 g, 90 mmol), prepared as described above, was dissolved in dichloromethane (700 ml). Triethylamine (27.2 g, 37.6 ml, 270 mmol) was added and the solution cooled to 0° C. After dropwise addition of neat trifluoroacetic anhydride (24.6 g, 16.5 ml, 117 mmol), the reaction was allowed to warm to room temperature and stirred for 1 h. The solution was concentrated in vacuo, the residue taken into ethyl acetate and then washed successively with hydrochloric acid (1N, 2×), water (1×), saturated aqueous sodium hydrogencarbonate (2×) and brine. Drying over sodium sulfate and removal of solvent gave a dark solid, which was purified by flash chromatography (400 g of silica gel, petroleum ether:ethyl acetate 7:3+1% MeOH as eluent) yielding 2-cyano-3-nitrothiophene 31 (13.4 g, 96.5%). 1H NMR (CDCl3): δ 7.75 (1H, d, J 5.5), 7.68 (1H, d, J 5.5). An analytical sample was obtained by recrystallization from dichloromethane/n-pentane, m.p. 87–88° C.; elemental analysis, calc. for C5H2N2O2S: C, 38.96; H, 1.31; N, 18.17; S, 20.80. Found: C, 38.92; H, 1.20; N, 18.03; S, 21.31.

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