Sodium hydride → Ethyl 5-(cyclopropylmethyl)-4-oxo-4,5,6,7-tetrahydropyrazolo[1,5-a]pyrazine-2-carboxylate

Participants

Reaction Steps

A 60% dispersion of sodium hydride in mineral oils (0.11 g, 2.74 mmol) was added to a stirred solution of 4,5,6,7-tetrahydro-4-oxo-pyrazolo[1,5-a]pyrazine-2-carboxylic acid ethyl ester (0.48 g, 2.28 mmol) in DMF (11.4 mL) at 0° C. The mixture was stirred at room temperature for 15 minutes and then bromomethylcyclopropane (0.26 mL, 2.74 mmol) was added. The mixture was stirred at room temperature for 16 hours, diluted with water and extracted with AcOEt. The organic layer was separated, washed with brine, dried (NaSO4), filtered and the solvents evaporated in vacuo. The crude product was purified by flash column chromatography (silica; AcOEt in DCM 0/100 to 40/60). The desired fractions were collected and the solvents evaporated in vacuo to yield 5-cyclopropylmethyl-4-oxo-4,5,6,7-tetrahydro-pyrazolo[1,5-a]pyrazine-2-carboxylic acid ethyl ester (0.32 g, 54% yield) as a white solid.

Provenance & Evidence