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

Temperature

100 °C

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.

1. customAfter the mixture was reacted at room temperature for 30 minutes
2. customreacted for 2 hours
3. temperatureThe mixture was cooled to room temperature
4. concentrationconcentrated under reduced pressure
5. customto remove acetic acid
6. extractionThe mixture was extracted with ethyl acetate (20 mL×3)
7. washThe combined organic extracts were washed with saturated brine
8. dry with materialdried over anhydrous sodium sulfate
9. filtrationfiltered
10. concentrationconcentrated under reduced pressure
11. customThe resulting residue was purified by silica gel column chromatography

ORD record

ord-65012b27fe494d05a9dc58cf62720416

Source dataset

uspto-grants-2013_02

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08367710B2