Dimethylformamide → N-[3-[(4aR,7aS)-2-Amino-4a-fluoro-5,7-dihydro-4H-furo[3,4-d][1,3]oxazin-7 a-yl]-4-fluoro-phenyl]-5-chloro-pyrazine-2-carboxamide

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Reaction Steps

Scheme 3, steps M, substep 2 or step N, substep 3 (amidation): A mixture of 5-chloropyrazine-2-carboxylic acid (1.53 g, 9.66 mmol) in acetonitrile (15 mL, 283 mmol) is treated with DMF (115 μL, 1.49 mmol) and oxalyl chloride (970 μL, 11.1 mmol). The mixture is stirred at ambient temperature under nitrogen for 20 minutes. In a separate flask is added (4aR,7aS)-7a-(5-amino-2-fluoro-phenyl)-4a-fluoro-5,7-dihydro-4H-furo[3,4-d][1,3]oxazin-2-amine (2.00 g, 7.43 mmol), ethanol (7.4 mL), water (7.4 mL) and the mixture is heated at 50° C. The acid chloride is added to the solution prepared above and the reaction mixture is stirred at 50° C. for 20 minutes. The reaction is cooled to room temperature, diluted with ethyl acetate (200 mL), and washed with water (40 mL) and saturated aqueous NaHCO3 (40 mL). The aqueous washes are combined and extracted with ethyl acetate (100 mL). The combined organic layers are dried (Na2SO4) and the solvent removed in vacuo to give the crude product. The crude product is purified by silica gel flash chromatography, eluting with ethyl acetate to give the title product (2.85 g, 94%). ES/MS (m/e): 410 (M+1)

Provenance & Evidence