反应详情

To a cold (−78° C.) solution of ethyl 6-bromo-8-methoxy-2-methyl-1-oxo-1,2,3,4-tetrahydropyrrolo[1,2-a]-pyrazine-7-carboxylate (0.5 g, 1.51 mmol; Example 7, steps 1 to 6, substituting benzyl bromide with iodomethane in step 5) in anhydrous THF (15 mL) under an atmosphere of dry nitrogen, a solution of n-BuLi in hexane (1.81 mL, 1.81 mmol, 1 M) was added. The resultant mixture was stirred at −78° C. for 15 minutes, and treated with methyl pyrazine-2-carboxylate (0.21 g, 1.51 mmol). The reaction mixture was allowed to warm up to room temperature, treated with dilute hydrochloric acid, and concentrated under vacuum. The residue was extracted with ethyl acetate. The organic extracts were combined, washed with aqueous sodium carbonate, dried over anhydrous magnesium sulfate, filtered and concentrated under vacuum. The residue was subjected to column chromatography on silica gel eluted with 0 to 10% methanol in ethyl acetate gradient. Collection and concentration of appropriate fractions provided the title compound.

1. concentrationconcentrated under vacuum
2. extractionThe residue was extracted with ethyl acetate
3. washwashed with aqueous sodium carbonate
4. dry with materialdried over anhydrous magnesium sulfate
5. filtrationfiltered
6. concentrationconcentrated under vacuum
7. washeluted with 0 to 10% methanol in ethyl acetate gradient
8. customCollection and concentration of appropriate fractions