Reaction #2467968

Reaction equation

methyl 4-hydroxy-5-(methoxycarbonyl)-3-nitrothiophene-2-carboxylate

potassium carbonate

Dimethyl sulfate

→

solid

Yield 45.0%

Methyl 4-methoxy-5-(methoxycarbonyl)-3-nitrothiophene-2-carboxylate

Yield 45.0%

Solvents

acetone

Conditions

Workup

1. 1
   workup.ADDITIONwas added to the above reaction mixture slowly
2. 2
   workup.ADDITIONa catalytic amount of KI was added
3. 3
   TemperatureThe mixture was refluxed for 4 h
4. 4
   Otherthe cooled reaction mixture
5. 5
   Filtrationwas filtered
6. 6
   Washthe solids were washed with acetone
7. 7
   OtherAcetone was removed under reduced pressure
8. 8
   Otherthe residue was chromatographed over silica gel column

Procedure

To a solution of methyl 4-hydroxy-5-(methoxycarbonyl)-3-nitrothiophene-2-carboxylate (650 mg, 2.5 mmol) in acetone (20 mL) was added potassium carbonate (0.68 g, 5 mmol) at it Dimethyl sulfate (0.36 mL, 3.73 mmol) was added to the above reaction mixture slowly with stirring and a catalytic amount of KI was added. The mixture was refluxed for 4 h and the cooled reaction mixture was filtered and the solids were washed with acetone. Acetone was removed under reduced pressure and the residue was chromatographed over silica gel column using hexane-ethyl acetate (90:10) as eluents to give the product as a pale yellow color solid (0.3 g, 45%), mp 80-82° C. 1H NMR (400 MHz, CDCl3): δ 4.08 (3H, s), 3.94 (3H, s), 3.92 (3H, s).

Source