Methanol → Methyl 4-hydroxythiophene-2-carboxylate
Reaction equation
S(Cl)(Cl)=O.[OH:5][C:6]1[CH:7]=[C:8]([C:11]([OH:13])=[O:12])[S:9][CH:10]=1.[CH3:14]O>>[OH:5][C:6]1[CH:7]=[C:8]([C:11]([O:13][CH3:14])=[O:12])[S:9][CH:10]=1Participants
4
Procedure
Thionyl chloride (1.6 ml) was added dropwise to a methanol solution (20 ml) of 4-hydroxythiophene-2-carboxylic acid (1.1 g, 7.6 mmol) under ice cooling. The solution mixture was refluxed with heating for 5 hours. The reaction solution was cooled to room temperature, poured into ice water and extracted with ethyl acetate. The extraction solution with ethyl acetate was dried over magnesium sulfate and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (n-hexane:ethyl acetate=4:1) and concentrated/dried under reduced pressure to obtain methyl 4-hydroxythiophene-2-carboxylate (0.7 g) as white powder.