反应详情

A solution of 50.6 g. of 4-amino-3,5-dimethoxy-benzoic acid methyl ester in 1 liter of absolute pyridine was treated during 30 minutes with 82 g. of carbobenzoxy chloride with stirring and ice-cooling. Thereafter, the mixture was stirred at room temperature for 20 hours. The pyridine was evaporated under vacuum and the residue treated with 1 liter of water and 3N hydrochloric acid to obtain a strongly acidic reaction. The resulting emulsion was extracted with two 1.5 liter portions of ethyl acetate. The ethyl acetate extract was washed with two 800 ml. portions of water, dried over magnesium sulfate and evaporated under vacuum. After recrystallization of the residue from ethyl acetate, there was obtained 2,6-dimethoxy-4-(methoxy-carbonyl)-carbanilic acid benzyl ester having a melting point of 132°-133° C.

1. temperatureice-cooling
2. customThe pyridine was evaporated under vacuum
3. additionthe residue treated with 1 liter of water and 3N hydrochloric acid
4. customto obtain
5. customa strongly acidic reaction
6. extractionThe resulting emulsion was extracted with two 1.5 liter portions of ethyl acetate
7. extractionThe ethyl acetate extract
8. washwas washed with two 800 ml
9. dry with materialportions of water, dried over magnesium sulfate
10. customevaporated under vacuum
11. customAfter recrystallization of the residue from ethyl acetate