Acetonitrile → (5R)-3-(2,2-Difluoro-4-methyl-3-oxo-3,4-dihydro-2H-1,4-benzoxazin-7-yl)-2-oxo-5-oxazolidinecarboxylic acid methyl ester

참여 물질

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To a stirred solution 2,2-difluoro-7-amino-4-methyl-4H-1,4-benzoxazin-3-one (Step 2, 1.05 g, 4.90 mmol) in acetonitrile (25 mL) is added LiOTf (841 mg, 5.39 mmol) followed by methyl-(R)-glycidate (549 mg, 5.39 mmol). The resulting mixture is heated to 50° C. over night at which time HPLC indicates complete consumption of the starting material. The reaction is quenched by addition of water (50 mL), EtOAc (100 mL) and saline (50 mL). The organic phase is separated followed by further extraction of the aqueous phase with EtOAc (20 mL×3). The combined organic phase is dried over Na2SO4, filtered and concentrated under reduced pressure, and the residue is passed through a short silica gel column (EtOAc) to remove the polar impurities from the amino alcohol intermediate (MS (m/z): 317.5 [M+H]+). This intermediate is dissolved in anhydrous acetonitrile (20 mL) followed by addition of CDI (1.58 g, 9.80 mmol, 2 eq. wrt aniline above) at room temperature. The resulting reaction mixture is stirred overnight at which time it is diluted with 0.1 N HCl (10 mL). The resulting pale yellow precipitate is filtered off, washed with additional 0.1 N HCl (25 mL) and water (100 mL) and dried under high vacuum to give the title compound (1.30 g, 77% for two steps), MS (m/z): 342.7 [M+H]+.

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