Hydrochloric Acid → 5-Methyl-2-(3-methyl-indan-5-yl)-2,4-dihydro-pyrazol-3-one

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Reaction Steps

Di-tert-butyl 1-(3-methyl-inden-5-yl)hydrazine-1,2-dicarboxylate 38e (1.05 g, 2.9 mmol) was dissolved in 16 mL of a solvent mixture of ethanol and water (V:V=5:3) under stirring, followed by successive addition of ethyl acetoacetate (0.377 mL, 2.9 mmol) and 1.45 mL of 6 N hydrochloric acid. The reaction mixture was heated to reflux and reacted for 1.5 hours under nitrogen atmosphere. The mixture was cooled to room temperature and the mixture was concentrated under reduced pressure to remove ethanol. The aqueous layer was extracted with dichloromethane (15 mL×3). The combined organic extracts were dried over anhydrous sodium sulfate, filtered and concentrated under reduced pressure. The residue was purified by silica gel column chromatography to obtain the title compound 5-methyl-2-(3-methyl-indan-5-yl)-2,4-dihydro-pyrazol-3-one 38f (103 mg, yield 15.6%) as a yellow oil.

Provenance & Evidence