反应详情

At −78° C., a solution of 4-phenylthiophene-2-carboxylic acid (800 mg, 3.92 mmol) in THF (10 mL) is treated with tert.-BuLi (8 mL, 1.6 M in pentane). The mixture is stirred at −70° C. for 40 min before iodomethane (1 mL) is added. Stirring is continued for 5 h at −78° C., then the reaction mixture is allowed to warm to rt overnight. The reaction is quenched with sat. aq. NH4Cl and extracted with EA. The organic extract is dried over MgSO4, the solvent is removed and the crude product is purified by CC on silica gel eluting with DCM containing 3% of methanol to give 5-ethyl-4-phenyl-thiophene-2-carboxylic acid (340 mg) as a red solid; LC-MS: tR=0.95 min, [M+1+MeCN]+=274.15; 1H NMR (CDCl3): δ 7.79 (s, 1H), 7.46-7.31 (m, 5), 2.92 (q, J=7.6 Hz, 2H), 1.30 (t, J=7.6 Hz, 3H).

1. additionis added
2. customThe reaction is quenched with sat. aq. NH4Cl
3. extractionextracted with EA
4. extractionThe organic extract
5. dry with materialis dried over MgSO4
6. customthe solvent is removed
7. customthe crude product is purified by CC on silica gel eluting with DCM containing 3% of methanol