Hydrochloric Acid → HCID 16723630, compound

Participants

Reaction Conditions

Reaction Steps

Under a nitrogen atmosphere, a mixture of 2-ethyl-2,5-dihydro-4H-pyrazolo[3,4-c]quinolin-4-one (10 g, 46.8 mmol), N,N,N′,N′-tetramethylethylenediamine (31 mL), and tetrahydrofuran (520 mL) was chilled to 0° C. A solution of n-butyllithium in hexanes (56 mL of 2.5 M) was added dropwise. After the addition was complete the reaction mixture was stirred for 5 minutes and then N,N-dimethylformamide (DMF, 72 mL) was added dropwise. The reaction mixture was warmed to ambient temperature and stirred for 1 hour. 1 N hydrochloric acid was added and the reaction mixture was stirred for 1 hour. The reaction mixture was concentrated under reduced pressure to about half the original volume and then diluted with water and extracted with dichloromethane. The combined extracts were dried over sodium sulfate, filtered, and then concentrated under reduced pressure to provide a dark yellow oil. The oil was combined with acetonitrile and stirred for 20 minutes. A bright yellow solid was isolated by filtration to provide 4 g of 2-ethyl-4-oxo-4,5-dihydro-2H-pyrazolo[3,4-c]quinoline-1-carbaldehyde as a yellow powder. MS (APCI) m/z 242 (M+H)+; 1H NMR (300 MHz, DMSO-d6) δ 11.67 (s, 1H), 10.52 (s, 1H), 8.72 (d, J=8.1 Hz, 1H), 7.49 (dt, J=1.4 and 7.3 Hz, 1H), 7.40 (dd, J1.4 and 8.3 Hz, 1H), 7.25 (dt, J=1.4 and 7.3 Hz, 1H), 4.82 (q, J=7.2 Hz, 2H), 1.52 (t, J=7.2 Hz, 3H). An additional 3 g of material was isolated from the mother liquor.

Provenance & Evidence