Reacción #2467989

Ecuación de reacción

2-aminothiophene-3-carboxamide

sodium nitrite

→

solid

Rendimiento 18.5%

3H-Thiopheno[2,3-d]1,2,3-triazin-4-one

Rendimiento 18.5%

Disolventes

sulfuric acid

sulfuric acid

Condiciones de reacción

Tratamiento posterior

1. 1
   workup.ADDITIONwhile adding
2. 2
   Otroshould keep between −5-0° C.
3. 3
   workup.ADDITIONAfter addition
4. 4
   workup.ADDITIONThe mixture was poured
5. 5
   Otrointo crushed ice slowly
6. 6
   workup.STIRRINGwith stirring for 15 min
7. 7
   workup.STIRRINGstirred at the same temperature for 15 min
8. 8
   ExtracciónThe solution was extracted with ethyl acetate (4×200 mL)
9. 9
   Lavadothe combined EtOAc layer was washed with water, brine
10. 10
    Secadodried over sodium sulfate
11. 11
    FiltraciónThe solution was filtered
12. 12
    Otroevaporated the solvent
13. 13
    OtroThe residue was chromatographed over silica gel column

Procedimiento

To an ice cold solution (0° C.) of 2-aminothiophene-3-carboxamide (5 g, 35.21 mmol) in concentrated sulfuric acid (40 mL) was added a cold (0° C.) solution of sodium nitrite (2.5 g, 35.21 mmol) in concentrated sulfuric acid (30 mL) for 30 min (while adding, the temperature should keep between −5-0° C.). After addition, the mixture was stirred at the same temperature (0° C.) for 3 h. The mixture was poured into crushed ice slowly with stirring for 15 min and stirred at the same temperature for 15 min. The solution was extracted with ethyl acetate (4×200 mL) and the combined EtOAc layer was washed with water, brine and dried over sodium sulfate. The solution was filtered and evaporated the solvent. The residue was chromatographed over silica gel column using chloroform-methanol (95:5) as eluents to give the product as a pale red color solid (1.0 g, 18%), mp 175-176° C. 1H NMR (400 MHz, DMSO-d6): δ 15.18 (1H, s), 8.16 (1H, d, J=5.6 Hz), 7.64 (1H, d, J=5.6 Hz); 13C NMR (100 MHz, DMSO-d6): δ 159.1, 153.8, 132.0, 126.1, 121.2; LC-MS (negative ion mode): m/z 152 (M−H)−.

Fuente