5-Fluoroisatin (I) is alkylated with 4-methylbenzyl bromide (II) in the presence of NaH to afford the N-benzyl isatin derivative (III). Then, Knoevenagel condensation of isatin (III) with cyanoacetic acid (IV) by means of triethylamine in dioxane gives the indolinylidene adduct (V) as a mixture of E and Z isomers. Subsequent catalytic hydrogenation of (V) over Pd/C then furnishes the target compound
5-Fluoroisatin (I) is alkylated with 4-methylbenzyl bromide (II) in the presence of NaH to afford the N-benzyl isatin derivative (III). Then, Knoevenagel condensation of isatin (III) with isopropyl cyanoacetate (IV) by means of piperidine in isopropanol gives the indolinylidene adduct (V) as a mixture of E and Z isomers. Subsequent catalytic hydrogenation of (V) over Pd/C then furnishes the target compound