Dimethyl acetylenedicarboxylate → HCID 44542635, compound

Participants

Reaction Steps

A 500 mL round-bottomed flask was charged with dimethyl but-2-ynedioate 70 (6.0 g, 42 mmol) and 50 mL of ether. To this solution was added a solution of 1-(4-(trifluoromethyl)phenyl)hydrazine 69 (7.6 g, 43 mmol) in 100 mL of ether over 30 min. After stirring at room temperature for 30 min, the reaction was concentrated and redissolved in MeOH (200 mL). The solution was added dropwise over 1 h to a NaOMe solution (made from sodium metal (3.9 g, 169 mmol) in 200 mL of MeOH). This mixture was stirred at room temperature for 1.5 h, the MeOH was removed, 100 mL of 5 N HCl was added, and the precipitate was collected by filtration. The solid was triturated with CH2Cl2 to give methyl 5-oxo-1-(4-(trifluoromethyl)phenyl)-4,5-dihydro-1H-pyrazole-3-carboxylate 71.

Provenance & Evidence