(4-Chlorophenyl)hydrazine → 3H-Pyrazolo[4,3-c]pyridin-3-one

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Reaction Steps

A mixture of 1.1 g of p-chlorophenylhydrazine and 1.9 of ethyl 4-chloro-6,7-dihydro-5H-cyclopenta[b]-pyridine-3-carboxylate (Example 2a) in 100 mL of n-butanol is refluxed for 24 hours under nitrogen atmosphere. The precipitate is collected and recrystallized from ethanol to yield 2-p-chlorophenyl-2,3,5,6,7,8-hexahydrocyclopentab]pyrazolo[3,4-d]pyridin-3-one, m.p. above 350°, showing IR peaks at 900, 835, 805, 798, 765, and 740 cm-1.

Provenance & Evidence