Hydrochloric Acid → methyl 5-oxo-1-phenyl-2,5-dihydro-1H-pyrazole-3-carboxylate

Participants

Reaction Conditions

Reaction Steps

Phenylhydrazine (0.5 g; 4.62 mmol), acetylenedicarboxylic acid dimethyl ester (0.66 g; 4.62 mmol) and 4-toluenesulfonic acid pyridine salt (1.16 g; 4.62 mmol) were dissolved in 7 ml of dry THF under nitrogen atmosphere and the solution was stirred for 2 h at RT after which 7 ml of 10% HCl (g) in EtOAc was added and the mixture heated at 67° C. for 5 h. The reaction mixture evaporated to dryness and 6 ml of DCM added to the residue. The organic phase was washed with 8 ml of water and the combined water phases were extracted with 2×6 ml of DCM. The combined organic phases were once more washed with 12 ml of water, dried over Na2SO4, filtered and evaporated to dryness to give 0.35 g of the product which was used as such without further purification.

Provenance & Evidence