N,N,N',N'-Tetramethylethylenediamine → HCID 57612926, compound

Participants

Reaction Conditions

Reaction Steps

To a round-bottomed flask containing 2-tert-butyl-2,5-dihydro-pyrazolo[3,4-c]quinolin-4-one (1.5 g, 6.2 mmol) was added tetrahydrofuran (20 mL) followed by N,N,N′,N′-tetramethylethylenediamine (3.6 g, 31.1 mmol). The reaction was stirred under nitrogen in an ice bath. To this suspension n-butyllithium (2.5 M in hexanes, 7.47 mL, 18.67 mmol) was added dropwise. The reaction mixture was cooled to −78° C. in an acetone-dry ice bath and tert-butyl 4-(2-iodoethyl)piperidine-1-carboxylate (2.3 g, 6.84 mmol) was added to the reaction. The reaction was warmed to ambient temperature over 30 minutes and stirred at that temperature for another 2 hours. Methanol 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 and the organic layer was washed with aqueous saturated sodium bicarbonate. The organic layer was separated, dried (magnesium sulfate), filtered, and evaporated to afford a dark oil. The product was purified twice by automated flash chromatography (Combiflash Separation System, eluted with a gradient of 0-5% methanol in dichloromethane with 1% ammonium hydroxide) to provide tert-butyl 4-[2-(2-tert-butyl-4-oxo-4,5-dihydro-2H-pyrazolo[3,4-c]quinolin-1-yl)-ethyl]-piperidine-1-carboxylate as a gray solid (0.17 g), mp 223-225° C.; MS (ESI) m/z 453 (M+H).

Provenance & Evidence