Iodoethane → HCID 66781363, compound

Participants

Reaction Steps

To a round-bottomed flask containing 2-tert-butyl-2,5-dihydropyrazolo[3,4-c]quinolin-4-one (20.0 g, 82.99 mmol) was added THF (500 mL) followed by N,N,N′,N′-tetramethylethylenediamine (48.13 g, 414.94 mmol). The reaction was stirred under a nitrogen atmosphere in an ice bath. To this suspension n-butyl lithium (2.5 M in hexanes, 130.0 mL, 324.91 mmol) was added dropwise. The reaction mixture was stirred in the ice bath for 2 minutes and then ethyl iodide (258.38 g, 1.66 mol) was added to the reaction. The reaction was stirred in the ice bath for 10 minutes and then the ice bath was removed. The reaction was stirred at ambient temperature overnight. Methanol (60 mL) was carefully added to quench the reaction and the solvent was evaporated to afford a dark oil. The oil was taken up in ethyl acetate (800 mL) and the organic layer was washed with water (3×600 mL). The organic layer was separated, dried (MgSO4), filtered, and evaporated to afford 2-tert-butyl-1-ethyl-2,5-dihydro-pyrazolo[3,4-c]quinolin-4-one (20.4 g) as a brown solid. A portion of this solid (15.2 g) was transferred to a round-bottomed flask and concentrated hydrochloric acid (410 mL) was added. The reaction was heated to 120° C. for 1 hour and then stirred at ambient temperature overnight. The solids in the reaction mixture were separated by filtration and washed with water. The solids were transferred to a round-bottomed flask and stirred in diethyl ether (100 mL) for 15 minutes. The product was isolated by filtration to afford 1-ethyl-2,5-dihydro-pyrazolo[3,4-c]quinolin-4-one as the hydrochloride salt. The product was stirred in 2N sodium hydroxide (60 mL) for 1.5 hours, filtered, washed with diethyl ether (600 mL), and dried under reduced pressure to afford 1-ethyl-2,5-dihydro-pyrazolo[3,4-c]quinolin-4-one as a tan brown solid (4.23 g).

Provenance & Evidence