Pyridine → 6-methyl-4H-pyrido[4,3-b][1,4]oxazine-3,5-dione

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Reaction Steps

To a solution of the title compound of Example 237, step 3 (1.6 g, 9.01 mmol, 1.00 Eq) in CH2Cl2 (150 mL) at 0° C. under N2 is added chloroacetyl chloride (0.75 mL, 9 mmol) dropwise. Pyridine (2.2 mL, 37 mmol) is then added, and the mixture was stirred for 5 h at room temperature. Saturated aqueous KHSO4 (100 mL) is added and the aqueous layer was extracted a total of three times with CH2Cl2. The combined organic layers were dried over Na2SO4, filtered, and then acetone (200 mL) followed by cesium carbonate (14.6 g, 45 mmol) were added directly to the filtrate (250 mL). The mixture was then heated at 50° C. for 2 h. The volume was reduced and water was added. Extractive work up with 3:1 CH2Cl2: isopropanol followed by trituration with 1:2 EA/PE gave the title compound (400 mg, yield: 24.67%) as a yellow solid. 1H NMR: (CDCl3, 400 MHz) δ: 8.17-8.14 (br, 1H), 7.01 (d, J=7.2 Hz, 1H), 6.07 (d, J=7.2 Hz, 1H), 4.69 (s, 1H), 3.59 (s, 3H). LCMS: 181.0 (M+H)+

Provenance & Evidence