Cesium carbonate → cyclobutyl (S)-4-acetyl-3-methyl-7-(1H-pyrazol-4-yl)-3,4-dihydroquinoxaline-1(2H)-carboxylate

Participants

Reaction Conditions

Reaction Steps

A 500-mL round-bottom flask was purged with nitrogen and charged with cyclobutyl (S)-4-acetyl-7-bromo-3-methyl-3,4-dihydroquinoxaline-1(2H)-carboxylate (15.0 g, 40.9 mmol), tert-butyl 4-(tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-pyrazole-1-carboxylate (20 g, 68 mmol), cesium carbonate (40.0 g, 123 mmol), [1,1′-bis(diphenylphosphino)ferrocene]dichloropalladium(II) dichloromethane complex (2.0 g, 2.45 mmol), 1,4-dioxane (150 mL), and water (15 mL). The resulting mixture was stirred overnight at 100° C. After cooling to room temperature, the reaction mixture was diluted with ethyl acetate (200 mL) and washed with water (100 mL). The combined organic phases were washed with brine (100 mL), dried over anhydrous sodium sulfate, filtered, and concentrated under vacuum. The residue was purified via column chromatography on silica gel (eluting with 1:3, ethyl acetate/petroleum ether) to afford cyclobutyl (S)-4-acetyl-3-methyl-7-(1H-pyrazol-4-yl)-3,4-dihydroquinoxaline-1(2H)-carboxylate (9.0 g, 62%) of as a yellow solid. MS (ESI, pos. ion) m/z 355 [M+H]+.

Provenance & Evidence