Hydrochloric Acid → 1,2-dimethyl-6,7-dihydrocyclopenta[e]indazol-8(2H)-one

Participants

Reaction Conditions

Reaction Steps

To a suspension of methyl 5-(3-methoxy-3-oxopropyl)-2,3-dimethyl-2H-indazole-4-carboxylate (666 mg, 2.29 mmol) and 60% sodium hydride (183 mg, 4.59 mmol) in tetrahydrofuran (23 mL) was added methanol (1 drop), and the mixture was heated under reflux for 3 hr. The reaction solution was concentrated to dryness to give yellow-brown crystals. The obtained crystals were gradually added to 12M hydrochloric acid (12 mL) heated to 100° C., and the mixture was stirred for 1 hr. The reaction solution was neutralized with 1M aqueous sodium hydroxide solution, and extracted with ethyl acetate. The extract was washed with saturated brine, and dried over anhydrous sodium sulfate. The solvent was evaporated under reduced pressure, and the residue was purified by silica gel column chromatography (ethyl acetate/hexane=20/80→70/30) to give the title compound (364 mg, yield 79%).

Provenance & Evidence