Reaction #2467981

Reaction equation

HCl

NaNO2

methyl 4-aminothiophene-2-carboxylate

K2CO3

dimethylamine

→

solid

Yield 10.8%

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

Yield 10.8%

Solvents

H2O

H2O

Conditions

Workup

1. 1
   workup.STIRRINGThe mixture was stirred at 0-5° C. for 1 h
2. 2
   workup.ADDITIONpoured into ice cold water
3. 3
   ExtractionThe solution was extracted with chloroform (3×100 mL)
4. 4
   WashThe combined CHCl3 layer was washed with water, brine
5. 5
   Dryingdried over sodium sulfate
6. 6
   FiltrationThe solution was filtered
7. 7
   Otherevaporated the solvent
8. 8
   OtherThe residue was chromatographed over silica gel column

Procedure

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).

Source