Bis(pinacolato)diborane → 6-(Imidazo[1,2-a]pyridin-7-ylamino)-4-methyl-5-oxo-4,5-dihydropyrazin-2-ylboronic Acid

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Reaction Conditions

Reaction Steps

A 100-mL round-bottomed flask equipped with a reflux condenser was charged with 185a (638 mg, 1.99 mmol), 4,4,4′,4′,5,5,5′,5′-octamethyl-2,2′-bi(1,3,2-dioxaborolane) (Pin2B2, 2.54 mg, 10 mmol), 1,1′-bis(diphenylphosphino)ferrocenedichloropalladium(II) (163 mg, 0.18 mmol), CS2CO3 (1.3 g, 3.98 mmol), and 1,4-dioxane (20 mL). After bubbling nitrogen through the mixture for 30 minutes, it was heated at 80° C. under nitrogen atmosphere for 3 h. The reaction mixture was cooled to room temperature and filtered. The filtrate was diluted with petroleum ether (150 mL) and ethyl acetate (15 mL). The resulting suspension was stirred at room temperature for 30 minutes. The solid was collected by filtration and further purified by silica-gel column chromatography eluting with dichloromethane/methanol (60/1 to 15/1) to afford 185b (400 mg, 70%) as an off-white solid. MS-ESI: [M+H]+ 286

Provenance & Evidence