反应详情

A stirred mixture of methyl 2-amino-4-chlorobenzoate (2.50 g, 13.5 mM) and dimethyl acetylenedicarboxylate (2.05 g, 14.4 mM) in t-butanol (22 mL) was refluxed for 7 hr under a nitrogen atmosphere. After adding additional dimethyl acetylenedicarboxylate (1.16 g, 8.13 mM) and refluxing another 2.5 hr, the reaction mixture was allowed to cool to room temperature and potassium t-butoxide (1.56 g, 13.9 mM) was added in one portion. A precipitate formed and the resulting mixture was refluxed for 1.5 hr. The mixture was cooled to room temperature and filtered to separate the solids, which were washed with t-butanol and ether. The solids were dissolved in water and acidified with 1N sulfuric acid to form a precipitate. The resulting mixture was extracted with methylene chloride and the combined extracts were washed with brine and water, dried (MgSO4), filtered and concentrated to give a green solid. Recrystallization of this material from methanol provided dimethyl 7-chloro-4-hydroxyquinoline-2,3-dicarboxylate (1.15 g, 28.9%) as an off-white solid, mp 232-233° C.; MS(CI): 296 (M+H).

1. temperaturewas refluxed for 7 hr under a nitrogen atmosphere
2. temperaturerefluxing another 2.5 hr
3. customA precipitate formed
4. temperaturethe resulting mixture was refluxed for 1.5 hr
5. temperatureThe mixture was cooled to room temperature
6. filtrationfiltered
7. customto separate the solids, which
8. washwere washed with t-butanol and ether
9. dissolutionThe solids were dissolved in water
10. customto form a precipitate
11. extractionThe resulting mixture was extracted with methylene chloride
12. washthe combined extracts were washed with brine and water
13. dry with materialdried (MgSO4)
14. filtrationfiltered
15. concentrationconcentrated
16. customto give a green solid
17. customRecrystallization of this material from methanol