Triethylamine → Sodium 5-phenyl-4,5-dihydro-1H-pyrazole-1-carboxylate

Ethyl chloroformate (12 g) was added dropwise under ice cooling to a solution of 14.6 g 5-phenyl-2-pyrazoline and 12 g triethylamine in 100 ml chloroform, and the mixture was stirred at room temperature for three hours. The reaction mixture was washed with 3% hydrochloric acid and 3% aqueous solution of sodium bicarbonate in that order and then dried over anhydrous sodium sulfate. The solvent was distilled off from the dried solution, and the oily residue thus obtained (20 g) was dissolved in 80 ml ethanol. To this ethanolic solution, was added 10 ml of 40% aqueous solution of caustic soda, the mixture was stirred at room temperature for one hour, and the crystals which precipitated out were collected by filtration and dried under reduced pressure, affording 12 g of pure product. M.p.: 210° C. (dec.); NMR (D2O): 2.6-3.4 (2H, m), 4.7 (1H, dd, J=12,5 Hz), 7.14 (1H, t, J=2 Hz), 7.40 (5H, s).

1. washThe reaction mixture was washed with 3% hydrochloric acid and 3% aqueous solution of sodium bicarbonate in that order
2. dry with materialdried over anhydrous sodium sulfate
3. distillationThe solvent was distilled off from the dried solution
4. customthe oily residue thus obtained (20 g)
5. stirringthe mixture was stirred at room temperature for one hour
6. customthe crystals which precipitated out
7. filtrationwere collected by filtration
8. customdried under reduced pressure

ORD record

ord-d7876466e5f5473dae08da8b048ca086

Source dataset

uspto-grants-1991_02

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US04990529