Trifluoroacetic acid → 2-(3,3-Dimethyl-indan-5-yl)-5-methyl-2,4-dihydro-pyrazol-3-one

Participants

Reaction Conditions

Reaction Steps

Di-tert-butyl 1-(3,3-dimethyl-1H-inden-5-yl)hydrazine-1,2-dicarboxylate 4b (2.70 g, 7.18 mmol) was dissolved in 100 mL of acetic acid followed by addition of 20 mL of trifluoroacetic acid. After the mixture was reacted at room temperature for 2 hours, ethyl acetoacetate (0.98 g, 7.54 mmol) was added. Then the mixture was heated to 100° C. and reacted for 2 hours. The mixture was cooled to room temperature and concentrated under reduced pressure to remove acetic acid. The reaction mixture was neutralized by saturated sodium bicarbonate solution, and then was extracted with ethyl acetate. The combined organic extracts were washed with saturated brine, dried over anhydrous sodium sulfate, filtered and concentrated under reduced pressure. The resulting residue was purified by silica gel column chromatography to obtain the title compound 2-(3,3-dimethyl-indan-5-yl)-5-methyl-2,4-dihydro-pyrazol-3-one 4c (1.0 g, yield 47.7%) as a light brown solid.

Provenance & Evidence