Phosphorus oxychloride → (3,5-Dichloro-4-methoxy-phenyl)-(2,3-dihydro-pyrido[4,3-b][1,4]oxazin-4-yl)-methanone

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Reaction Steps

To a mixture of 3,4-dihydro-2H-pyrido[4,3-b][1,4]oxazine (80 mg, 0.58 mmol) and 3,5-dichloro-4-methoxy-benzoic acid (141 mg, 0.64 mmol), phosphorus oxychloride (4 ml) was added and then stirred at 100□ for 12 hours. The reaction mixture was cooled to 0□ and adjusted to pH of 8-9 by using saturated solution of sodium hydrogen carbonate and extracted with ethyl acetate. The combined organic layer was washed with saturated saline solution, dried over anhydrous sodium sulfate (Na2SO4), filtered and evaporated under reduced pressure. The residue was purified by column chromatography on silica eluting with a solvent of n-hexane:ethyl acetate=4:1. The fractions containing the product were collected and evaporated to obtain white solid (107 mg, 54%).

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