Dimethyl 4-aminoisophthalate → Dimethyl-4-(2'-ethoxy-3'-methoxy-benzoylamino)-isophthalate

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Reaction Steps

Dimethyl- 4-amino-isophthalate (5 g) in 50 ml of dioxane and 10 ml of anhydrous pyridine is treated with 7.5 g of 2-ethoxy-3-methoxybenzoyl chloride at room temperature, overnight. After dilution with water, the precipitate is collected, dissolved in ethyl acetate, and washed with 5% NaHCO3 and then with water. After evaporation to dryness under vacuum, the material is crystallized from isopropyl ether, yielding dimethyl- 4-(2'-ethoxy-3'-methoxy-benzoylamino)-isophthalate (9 g; m.p. 113°-115° C.), which is dissolved in 80 ml of dioxane and treated with 70 ml of 1N NaOH at room temperature for 4 hours. After acidification with diluted HCl, the precipitate is collected under vacuum and washed with water until neutral. The yield is 7.4 g of 4-(2'-ethoxy-3'-methoxy-benzoylamino)-isophthalic acid (m.p.=244°-246° C.), which are treated with 10 ml of acetic anhydride at the reflux temperature for 10'.

Provenance & Evidence