Diethyl Malonate → 5-chloro-1H-pyrrolo[3,2-b]pyridin-2(3H)-one

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Reaction Steps

The mixture containing 3-amino-2-bis(ethoxycarbonyl)methyl-6-chloropyridine, 3-amino-6-bis(ethoxycarbonyl)methyl-2-chloropyridine and diethyl malonate was taken up in 6N HCl solution (700 mL) and heated at reflux for 5 hours. After removing the aqueous acid in vacuo, the residue was taken up in water and again concentrated to yield 5-chloro-4-azaoxindole as a brown solid which was dried in the air. The yield was 7.04 g. (32% overall from 2,6-dichloro-3-nitropyridine). An analytical sample was prepared by recrystallization from isopropanol; m.p. 250°-254° C. (dec.).

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