反应详情

温度

-78 °C

A solution of methyl 3-methylthiophene-2-carboxylate 109a (33 g, 0.211 mol) in dry CH2Cl2 (30 mL) was added dropwise to a mixture of aluminum chloride (40 g, 0.297 mol) and dry CH2Cl2 (200 mL) at −78° C., under nitrogen. The reaction mixture was stirred for 10 min at −78° C., and a solution of tert-butyl chloride (23 mL, 0.211 mol) in dry CH2Cl2 (30 mL) was added dropwise at −78° C. The reaction mixture was stirred for 1 h at −78° C., gradually allowed to warm to room temperature and stirred for 16 h at room temperature. It was poured on ice and extracted with CH2Cl2 (2×200 mL). The organic layer was dried over anhydrous Na2SO4 and the solvent evaporated under vacuum. The obtained residue was purified by fractional distillation to yield methyl 5-tert-butyl-3-methylthiophene-2-carboxylate 109b (19 g, 43%) as a light yellow liquid.

1. stirringThe reaction mixture was stirred for 1 h at −78° C.
2. temperatureto warm to room temperature
3. stirringstirred for 16 h at room temperature
4. additionIt was poured on ice
5. extractionextracted with CH2Cl2 (2×200 mL)
6. dry with materialThe organic layer was dried over anhydrous Na2SO4
7. customthe solvent evaporated under vacuum
8. distillationThe obtained residue was purified by fractional distillation