METHYL BENZO[B]THIOPHENE-2-CARBOXYLATE

Application

Methylbenzothiophene-2-carboxaldehyde is an organic synthesis intermediate used in laboratory research and development processes and in chemical and pharmaceutical synthesis. It is obtained by esterification of benzothiophene-2-carboxylate. It can be used to synthesize 2-substituted-1,3,4-oxadiazine ones – compound 4.

Synthesis

General procedure for the synthesis of methylbenzothiophene-2-carbaldehyde from methanol and benzothiophene-2-carboxylic acid: 2-benzothiophenecarboxylic acid (1.0 g, 5.61 mmol, 1.0 eq.) was dissolved in 20 mL of methanol, followed by the addition of concentrated sulfuric acid (0.1 g) as catalyst. The reaction mixture was stirred at 60 °C for 16 hours. Upon completion of the reaction, 50 mL of saturated aqueous sodium bicarbonate was added to the reaction mixture to neutralize the acidic conditions. Subsequently, the organic phase was separated by extraction with ethyl acetate. The organic phase was sequentially washed with saturated brine and dried over anhydrous sodium sulfate. Finally, the organic phase was concentrated under reduced pressure to afford the target product methyl 2-benzothiophenecarboxylate (1.05 g, 97.4% yield) as a white solid.

References

[1] Synlett, 2004, # 6, p. 1113 - 1116
[2] Patent: CN107383024, 2017, A. Location in patent: Paragraph 0407