反应详情

温度

-78 °C

To a solution of 4-isobutyl-3-methyl-thiophene-2-carboxylic acid (991 mg, 5.0 mmol) in THF (30 mL), tert.-BuLi (7.3 mL, 11 mmol, 1.5 M in pentane) is slowly added at −78° C. The mixture is stirred at −78° C. for 1 h, then iodomethane (1.6 mL, 25.7 mmol) is added. The mixture is stirred and is allowed to warm to rt over a period of 15 h before the reaction is quenched with 1 N aq. HCl (50 mL) and extracted with DCM (1×100 mL, 2×50 mL). The combined organic extracts are dried (MgSO4), filtered and evaporated. The residue is purified by CC on silica gel eluting with a gradient of EA in hexane to give 3-ethyl-4-isobutyl-thiophene-2-carboxylic acid (325 mg) as a yellow solid; LC-MS: tR=0.98 min, 1H NMR (CD3OD): δ 7.22 (s, 1H), 2.94 (q, J=7.6 Hz, 2H), 2.42 (d, J=7.0 Hz, 2H), 1.86 (hept, J=7.0 Hz, 1H), 1.11 (t, J=7.6 Hz, 3H), 0.93 (d, J=7.0 Hz, 6H).

1. stirringThe mixture is stirred
2. temperatureto warm to rt over a period of 15 h before the reaction
3. customis quenched with 1 N aq. HCl (50 mL)
4. extractionextracted with DCM (1×100 mL, 2×50 mL)
5. dry with materialThe combined organic extracts are dried (MgSO4)
6. filtrationfiltered
7. customevaporated
8. customThe residue is purified by CC on silica gel eluting with a gradient of EA in hexane