反应详情

In tetrahydrofuran (66 mL) was dissolved methyl 5-chloropyrazine-2-carboxylate (3.3 g), and 1M diisobutylaluminum hydride/hexane solution (38.3 mL) was added dropwise to the solution under nitrogen atmosphere at −70° C. or lower over 10 minutes, and the resulting mixture was further stirred for 10 minutes. At −60° C. or lower, 1M diisobutylaluminum hydride/hexane solution (31.3 mL) was added dropwise to the mixture over 20 minutes, and the mixture was further stirred at −70° C. or lower for 1 hour. The reaction mixture was poured into a saturated aqueous ammonium chloride solution, and after stirring at room temperature, filtered with Celite. The filtrate was extracted with ethyl acetate, washed with a saturated brine, dried over anhydrous magnesium sulfate, and concentrated under reduced pressure. The obtained residue was purified by silica gel column chromatography (n-hexane:ethyl acetate=100:0 to 80:20) to obtain 5-chloropyrazine-2-carbaldehyde (970 mg).

1. additionwas added dropwise to the solution under nitrogen atmosphere at −70° C. or lower over 10 minutes
2. stirringthe mixture was further stirred at −70° C. or lower for 1 hour
3. stirringafter stirring at room temperature
4. filtrationfiltered with Celite
5. extractionThe filtrate was extracted with ethyl acetate
6. washwashed with a saturated brine
7. dry with materialdried over anhydrous magnesium sulfate
8. concentrationconcentrated under reduced pressure
9. customThe obtained residue was purified by silica gel column chromatography (n-hexane:ethyl acetate=100:0 to 80:20)