Dimethyl 3-nitrophthalate (I) was hydrogenated in the presence of Pd/C to give aminophthalate (II), which was acylated with Ac2O in pyridine, yielding acetamidophthalate (III). Condensation of phthalate ester (III) with 4'-methoxyacetophenone (IV) using NaH in DMF produced triketone (V). After acid hydrolysis of the amide function of (V), the resulting aminoindenetrione (VI) was cyclized with hydrazine hydrate to generate the indenopyrazolone system (VII). Condensation of (VII) with phenyl chloroformate afforded the phenyl carbamate (VIII). This was finally treated with concentrated ammonia to furnish the target urea derivative.
Dimethyl 3-nitrophthalate (I) was hydrogenated in the presence of Pd/C to give aminophthalate (II), which was acylated with Ac2O in pyridine, yielding acetamidophthalate (III). Condensation of phthalate ester (III) with 4-acetyl-2-chlorothiophene (IV) using NaH in DMF produced triketone (V). After acid hydrolysis of the amide function of (V), the resulting aminoindenetrione (VI) was cyclized with hydrazine hydrate to generate the indenopyrazolone system (VII). Condensation of (VII) with phenyl chloroformate afforded the phenyl carbamate (VIII). This was finally treated with concentrated ammonia to furnish the target urea derivative.
Catalytic hydrogenation of dimethyl 3-nitrophthalate (I) in the presence of Pd/C afforded the corresponding amino derivative (II), which was subsequently acetylated with Ac2O in pyridine yielding amide (III). Claisen condensation of diester (III) with 4'-methoxyacetophenone (IV) using NaH in hot DMF furnished the indandione (V). The tricarbonyl intermediate (V) was then treated with hydrazine to give the indenopyrazole (VI) as a single regioisomer. Acidic hydrolysis of the acetamide function of (VI) provided amine (VII). This was finally converted to the target formamide derivative upon heating with neat formic acid.