Dimethylformamide → 5-Phenylthiophene-2-carbaldehyde
Reaction equation
P(Cl)(Cl)(Cl)=O.[C:6]1([C:12]2[S:13][CH:14]=[CH:15][CH:16]=2)[CH:11]=[CH:10][CH:9]=[CH:8][CH:7]=1.[OH-].[Na+].CN(C)[CH:21]=[O:22]>>[CH:21]([C:14]1[S:13][C:12]([C:6]2[CH:7]=[CH:8][CH:9]=[CH:10][CH:11]=2)=[CH:16][CH:15]=1)=[O:22]Participants
5
Procedure
Under a nitrogen atmosphere 75 mL of dimethylformamide was cooled to 0° C., and 15 mL of phosphorus oxychloride was added with stirring. The solution was allowed to warm to room temperature, and then a solution of 20.4 grams (0.127 mole) of 2-phenylthiophene in 20 mL of dimethylformamide was added in one portion. The reaction mixture was heated to 80° C. where it stirred for 24 hours. It was then poured into 250 mL of an aqueous, 10% sodium hydroxide solution containing 50 grams of ice. The resulting slurry was extracted with chloroform, and the extract was washed in succession with an aqueous solution saturated with sodium chloride and water. The organic phase was dried over anhydrous magnesium sulfate and filtered. TThe filtrate was concentrated under reduced pressure to a brown residue. Purification of this residue by column chromatography on silica gel, eluting with ethyl acetate:n-hexane (15:85) yielded 18.0 grams of 2-formyl-5-phenylthiophene.