Phthalic Anhydride → 4-(4-Bromophenyl)-2-(1,3-dioxo-1,3-dihydroisoindol-2-yl)-thiophene-3-carboxylic acid ethyl ester

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Reaction Steps

A mixture of 2-amino-4-(4-bromophenyl)-thiophene-3-carboxylic acid ethyl ester (2 mmol, Example 21, Part B) and phthalic anhydride (2.2 mmol) in glacial acetic acid (20 mL) is heated at reflux overnight. After cooling to room temperature, the acetic acid is removed in vacuo and the residue triturated with petroleum ether. The crude product is collected by filtration, suspended in acetyl chloride (5 mL), and heated to reflux for one hour. After removing the solvent in vacuo, the residue is dissolved in ethyl acetate (30 mL), washed sequentially with 5% aqueous NaHCO3 (10 mL), water (10 mL), brine (10 mL), dried (Na2SO4), filtered, and concentrated in vacuo. Recrystallization affords the desired product.

Provenance & Evidence