Reaction #2467972

Reaction equation

K2CO3

dimethylamine

methyl 3-amino-5-phenylthiophene-2-carboxylate

HCl

NaNO2

→

solid

Yield 76.0%

Methyl 3-[(dimethylamino)diazenyl]-5-phenylthiophene-2-carboxylate

Yield 76.0%

Solvents

H2O

H2O

acetone

Conditions

Workup

1. 1
   workup.DISSOLUTIONto dissolve the product
2. 2
   workup.STIRRINGThe mixture was stirred at 0-5° C. for 1 h
3. 3
   workup.ADDITIONpoured into ice cold water
4. 4
   ExtractionThe solution was extracted with chloroform (3×100 mL)
5. 5
   WashThe combined CHCl3 layer was washed with water, brine
6. 6
   Dryingdried over sodium sulfate
7. 7
   FiltrationThe solution was filtered
8. 8
   Otherevaporated the solvent
9. 9
   OtherThe residue was chromatographed over silica gel column

Procedure

To a solution of methyl 3-amino-5-phenylthiophene-2-carboxylate (5 g, 21.4 mmol) and conc. HCl (9 mL, 85.8 mmol) in H2O (51 mL) was added acetone (30 mL) to dissolve the product. Then NaNO2 (1.7 g, 23.6 mmol) was added in portions for 15 min at 0° C. After stirring at 0-5° C. for 1 h, the reaction mixture was added to the solution of K2CO3 (11.2 g, 81.5 mmol) and dimethylamine (8.5 mL, 40%, 77.2 mmol) in H2O (60 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 (90:10) as eluents to give the product as a pale brown color solid (3.8 g, 76%), mp 92-94° C. 1H NMR (400 MHz, DMSO-d6): δ 7.78-7.80 (2H, m), 7.64 (1H, s), 7.46-7.52 (3H, m), 3.84 (3H, s), 3.60 (3H, s), 3.28 (3H, s); LC-MS (positive ion mode): m/z 290 (M+H)+.

Source