N,N'-Dimethylethylenediamine → 5-(4-Fluorophenyl)-4-oxo-4,5,6,7-tetrahydro-pyrazolo[1,5-a]pyrazine-2-carboxylic acid ethyl ester

Participants

Reaction Conditions

Reaction Steps

Copper (I) iodide (0.18 g, 0.95 mmol) was added to a suspension of 4,5,6,7-tetrahydro-4-oxo-pyrazolo[1,5-a]pyrazine-2-carboxylic acid ethyl ester (1.0 g, 4.78 mmol), 1-bromo-4-fluorobenzene (1.0 mL, 9.56 mmol), N,N′-dimethylethylenediamine (0.30 mL, 2.86 mmol) and K2CO3 (1.3 g, 9.56 mmol) in toluene (20 mL). The reaction mixture was stirred at 130° C. for 16 hours. The mixture was filtered through a pad of diatomaceous earth which was washed with AcOEt. The mixture was diluted with AcOEt and washed with a 16% aqueous solution of NH4OH. The organic layer was separated, dried (Na2SO4), filtered and the solvents evaporated in vacuo. The crude product was purified by flash column chromatography (silica; AcOEt in DCM 0/100 to 30/70). The desired fractions were collected and the solvents evaporated in vacuo to yield 5-(4-fluorophenyl)-4-oxo-4,5,6,7-tetrahydro-pyrazolo[1,5-a]pyrazine-2-carboxylic acid ethyl ester (1.3 g, 90% yield) as a white solid.

Provenance & Evidence