Cesium carbonate → tert-Butyl 8-(4-(benzyloxy)-2-oxopyridin-1(2H)-yl)-3,4-dihydropyrazino[1,2-a]benzimidazole-2(1H)-carboxylate

Participants

Reaction Conditions

Reaction Steps

tert-Butyl 8-bromo-3,4-dihydropyrazino[1,2-a]benzimidazole-2(1H)-carboxylate (188 mg, 0.534 mmol), 4-(benzyloxy)pyridin-2(1H)-one (118 mg, 0.589 mmol), CuI (203 mg, 1.07 mmol), trans-N,N′dimethylcyclohexane-1,2-diamine (76 mg, 0.54 mmol) and Cs2CO3 (192 mg, 0.591 mmol) in 1,4-dioxane (15 mL) were sparged with a nitrogen stream for 45 min and then stirred at 110° C. for 16 h. The mixture was diluted with 90:9:1 CH2Cl2/MeOH/NH4OH (50 mL) and washed with brine (3×50 mL). The resulting solution was dried over Na2SO4 and concentrated under reduced pressure to give a crude residue. The residue was purified by column chromatography eluting with methylene chloride and a 9:1 methanol/ammonium hydroxide mixture; gradient 100% methylene chloride to 85% methylene chloride, to provide the title compound (131 mg, 28%) as a brown solid: ESI MS m/z 473 [M+H]+.

Provenance & Evidence