6-(4-Tert-butyl-phenyl)-4-oxo-4,5-dihydro-pyrazolo[1,5-a]pyrazine-2-carboxylic acid → 6-(4-tert-butyl-phenyl)-5H-pyrazolo[1,5-a]pyrazin-4-one

Participants

Reaction Conditions

Reaction Steps

28.9 mg (0.454 mmol) Copper powder is added to a solution of 70.7 mg (0.227 mmol) 6-(4-tert-butyl-phenyl)-4-oxo-4,5-dihydro-pyrazolo[1,5-a]pyrazine-2-carboxylic acid in 2 ml quinoline. The mixture is stirred at 190° C. for 20 hours. Quinoline is distilled off under vacuum and the residue is chromatographed on a silica gel column with cyclohexane/ethyl acetate as eluent to give 6-(4-tert-butyl-phenyl)-5H-pyrazolo[1,5-a]pyrazin-4-one as colourless crystals; HPLC/MS: 1.88 (C), [M+H] 268; 1H NMR (400 MHz, DMSO-d6) δ [ppm] 11.49 (s, 1H), 8.03 (s, 1H), 7.92 (d, J=2.2, 1H), 7.69 (d, J=8.5, 2H), 7.49 (d, J=8.6, 2H), 7.01 (d, J=1.6, 1H), 1.32 (s, 9H).

Provenance & Evidence