تفاعل #8801

معادلة التفاعل

amide

3-nitrothiophene-2-carboxamide

Triethylamine

trifluoroacetic anhydride

→

2-cyano-3-nitrothiophene

المردود 96.6%

المذيبات

dichloromethane

ظروف التفاعل

المعالجة

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

الإجراء التجريبي

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.

المصدر