Dichloromethane → 3-CinnolinecarboxaMide, 4-aMino-8-(2-fluoro-6-Methoxyphenyl)-N-propyl-

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Reaction Steps

A 2 L, 3-necked flask equipped with a reflux condenser, mechanical stirrer, and 250 mL addition funnel was charged with 4-amino-8-bromo-N-propyl-cinnoline-3-carboxamide (36.80 g, 119.09 mmol), 2-fluoro-6-methoxy-phenylboronic acid (60.70 g, 357.06 mmol), and Pd(dppf)Cl2.CH2Cl2 (7.40 g, 9.06 mmol) under Argon at ambient temperature. A gentle vacuum was applied and the apparatus was back-filled with Argon two times. Tetrahydrofuran (515 mL, anhydrous) and isopropanol (147 mL, anhydrous) were added and the resulting red suspension was stirred at room temperature for 15 minutes. A solution of sodium carbonate (57.0 g, 537.7 mmol) in water (220 mL) was added rapidly through the addition funnel and the resulting mixture immediately placed into a pre-heated 80° C. oil bath. After 90 minutes at reflux (observed internal temperature 65° C.), the reaction mixture was cooled to room temperature and filtered though a bed of Celite supported on a sintered glass funnel topped with Norite decolorizing carbon (30 g). The residual salts and filter-cake were washed with 4:1 (v/v) THF:isopropanol until no additional material could be detected in the eluent by TLC (silica gel, 1:1 (v/v) hexanes:ethyl acetate, UV detection, Rf=0.25). The dark red solution was concentrated to a small volume under reduced pressure and then diluted with ethyl acetate (250 mL). The organic phase was separated and the aqueous phase extracted with ethyl acetate (2×250 mL). The combined organic layers were washed with brine, dried over sodium sulfate, filtered and then concentrated under reduced pressure. The residues were passed through a small pad of silica gel on a sintered glass funnel washing with ethyl acetate until no more material was detected in the eluent. The solution was evaporated to afford the crude product as a foamy red-brown solid. This material was purified by flash chromatography on silica gel using a gradient of 40 to 50% ethyl acetate in hexanes. Product containing fractions were combined and evaporated. The residue was precipitated from dichloromethane by addition of hexanes at room temperature. Recrystallization of this material from hot 1:1 (v/v) ethanol:water afforded the title compound as off-white white crystals (32.78 g, 78% yield). Additional title compound (4.30 g, 10% yield) was isolated by processing the residues form the crystallization liquors through an acid-base extractive workup.

Provenance & Evidence