Trifluoroacetic acid → 5-Methyl-2-(1,1,3,3-tetramethyl-indan-5-yl)-2,4-dihydro-pyrazol-3-one

Participants

Reaction Conditions

Reaction Steps

Di-tert-butyl 1-(1,1,3,3-tetramethyl-2,3-dihydro-1H-inden-5-yl)hydrazine-1,2-dicarboxylate 19c (2.70 g, 7.18 mmol) was dissolved in 10 mL of acetic acid followed by addition of 13 mL of trifluoroacetic acid. After the mixture was reacted at room temperature for 30 minutes, ethyl acetoacetate (502 mg, 3.86 mmol) was added. The reaction mixture was heated to 100° C. and reacted for 2 hours. The reaction was monitored by TLC until the disappearance of the starting materials. The mixture was cooled to room temperature and concentrated under reduced pressure to remove acetic acid. The mixture was neutralized by saturated aqueous sodium bicarbonate. The mixture was extracted with ethyl acetate (20 mL×3). 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 5-methyl-2-(1,1,3,3-tetramethyl-indan-5-yl)-2,4-dihydro-pyrazol-3-one 19d (130 mg, yield 13.6%) as a light yellow oil.

Provenance & Evidence