反应详情

To a solution of ethyl 5-bromo-2-ethylthiophene-3-carboxylate (5.00 g) synthesized in Example 69 (4) in tetrahydrofuran (50 mL) was added dropwise 1.0M isopropylmagnesium bromide-tetrahydrofuran solution (28.5 mL) at −40° C., and the mixture was stirred for 1.5 hr under an argon atmosphere. Isobutylaldehyde (8.67 mL) was added dropwise, and the mixture was stirred at −40° C. for 1 hr and at room temperature for 1 hr. Saturated aqueous ammonium chloride solution was added to quench the reaction, and the mixture was extracted with ethyl acetate. The extract was washed with brine, dried over magnesium sulfate, and concentrated under reduced pressure. To a solution of the residue in trifluoroacetic acid (50 mL) was added triethylsilane (9.10 mL), and the mixture was stirred at room temperature for 3 hr, and concentrated under reduced pressure. The residue was purified by silica gel column chromatography (ethyl acetate:hexane=1:24, volume ratio) to give the title compound (3.67 g, 80%) as a pale-yellow oil.

1. stirringthe mixture was stirred at −40° C. for 1 hr and at room temperature for 1 hr
2. customto quench
3. customthe reaction
4. extractionthe mixture was extracted with ethyl acetate
5. washThe extract was washed with brine
6. dry with materialdried over magnesium sulfate
7. concentrationconcentrated under reduced pressure
8. additionTo a solution of the residue in trifluoroacetic acid (50 mL) was added triethylsilane (9.10 mL)
9. stirringthe mixture was stirred at room temperature for 3 hr
10. concentrationconcentrated under reduced pressure
11. customThe residue was purified by silica gel column chromatography (ethyl acetate:hexane=1:24, volume ratio)