反应详情

A solution of 12.0 g (79.95 mmol) of 2,3-pyrazine dicarboxylic anhydride in 282 mL of MeOH was heated to 65° C. overnight. The reaction mixture was cooled to ambient temperature and concentrated in vacuo. To the obtained residue was added water followed by slow addition of solid NaHCO3. After gas evolution ceased, the aqueous layer was extracted with EtOAc (1×). The aqueous layer was then acidified to pH 2 by addition of conc. HCl. The aqueous layer was extracted with EtOAc (2×) and the combined organics from the second extraction washed with brine (1×). The organic layer was dried over Na2SO4, filtered and concentrated in vacuo to yield 12.41 g (85% crude yield) of 3-(methoxycarbonyl)pyrazine-2-carboxylic acid (Compound 6) as a white powder that was used without further purification: 1H NMR (DMSO, 300 MHz): δppm 8.91 (d, J=2.7 Hz, 1H), 8.89 (d, J=2.7 Hz, 1H), 3.91 (s, 3H).

1. concentrationconcentrated in vacuo
2. additionTo the obtained residue was added water
3. additionfollowed by slow addition of solid NaHCO3
4. extractionthe aqueous layer was extracted with EtOAc (1×)
5. additionThe aqueous layer was then acidified to pH 2 by addition of conc. HCl
6. extractionThe aqueous layer was extracted with EtOAc (2×)
7. extractionthe combined organics from the second extraction
8. washwashed with brine (1×)
9. dry with materialThe organic layer was dried over Na2SO4
10. filtrationfiltered
11. concentrationconcentrated in vacuo