Reaction #3201

Reaction equation

methyl 2-amino-4,6-dichlorobenzoate

dimethyl acetylenedicarboxylate

potassium t-butoxide

→

title compound

Yield 59.0%

Dimethyl 5,7-dichloro-4-hydroxyquinoline-2,3-dicarboxylate

Yield 59.0%

Solvents

t-butanol

Conditions

Workup

1. 1
   Otherformed
2. 2
   TemperatureAfter refluxing for 1.5 hr
3. 3
   Temperaturethe reaction mixture was cooled to room temperature
4. 4
   Filtrationfiltered
5. 5
   Otherto separate the precipitated solids
6. 6
   WashThe solids were washed with t-butanol
7. 7
   workup.DISSOLUTIONdissolved in water
8. 8
   Otherthe resulting precipitate was collected
9. 9
   Washwashed thoroughly with water
10. 10
    Otherdried

Procedure

A solution of methyl 2-amino-4,6-dichlorobenzoate (1.30 g, 5.91 mM) and dimethyl acetylenedicarboxylate (0.96 g, 6.78 mM) in t-butanol (14 mL) was refluxed for 18 hr under a nitrogen atmosphere. The reaction mixture was cooled to room temperature and potassium t-butoxide (0.76 g, 6.8 mM) was added to the stirred mixture whereupon a precipitate formed. After refluxing for 1.5 hr, the reaction mixture was cooled to room temperature and filtered to separate the precipitated solids. The solids were washed with t-butanol and then dissolved in water. The resulting solution was acidified with 1N H2SO4 and the resulting precipitate was collected, washed thoroughly with water and dried to give the title compound as a light green solid (1.15 g, 59%). An analytical sample was obtained by recrystallization of a portion from toluene to provide the title compound as a light tan solid, mp 109.5°-111° C. (d); MS(CI): 330 (M+H).

Source