Hydrochloric Acid → Methyl 4-[(dimethylamino)diazenyl]thiophene-2-carboxylate

Temperature

2.5 °C

To a solution of methyl 4-aminothiophene-2-carboxylate (1.7 g, 10.82 mmol) and cone. HCl (4.6 mL, 43.5 mmol) in H2O (20 mL) was added NaNO2 (0.84 g, 12.17 mmol) in portions for 5 min at 0° C. After stirring for 0.5 h at 0-5° C., the reaction mixture was added to the solution of K2CO3 (5.8 g, 42 mmol) and dimethylamine (4.6 mL, 40%, 40.9 mmol) in H2O (30 mL) at 0° C. The mixture was stirred at 0-5° C. for 1 h and poured into ice cold water. The solution was extracted with chloroform (3×100 mL). The combined CHCl3 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 hexane-EtOAc (80:20) as eluents to give the product as light red color solid (250 mg), which was recrystallized from chloroform-hexane (110 mg), mp 90-92° C. 1H NMR (400 MHz, CDCl3): δ 7.93 (1H, d, J=1.6 Hz), 7.31 (1H, d, J=1.6 Hz), 3.88 (3H, s), 3.31 (6H, br s).

1. stirringThe mixture was stirred at 0-5° C. for 1 h
2. additionpoured into ice cold water
3. extractionThe solution was extracted with chloroform (3×100 mL)
4. washThe combined CHCl3 layer was washed with water, brine
5. dry with materialdried over sodium sulfate
6. filtrationThe solution was filtered
7. customevaporated the solvent
8. customThe residue was chromatographed over silica gel column

ORD record

ord-bf1c337be5db4f2494f51162280453f0

Source dataset

uspto-grants-2012_09

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08258119B2