Methanol → 3-Oxo-3,4-dihydro-2H-1,4-benzoxazine-6-carboxylic acid

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Reaction Steps

In a 250 ml round-bottomed flask were place the preceding methyl 1,4-benzoxazine-3-one-6-carboxylate (5.8 g, 28 mmole), 50% aqueous sodium hydroxide (9.0 g, 112 mmole), methanol (125 ml), and water (19 ml). The resulting mixture was refluxed for 4 hours. The reaction mixture was cooled to room temperature and the solvent eliminated in the rotary evaporator. The crude reaction product was taken up in water and the resulting aqueous solution was washed with hexane (2×50 ml) and acidified to pH=1 with concentrated aqueous hydrochloric acid. The solid which formed was separated by suction filtration, and dried in a vacuum oven yielding 5.1 g of the expected 1,4-benzoxazine-3-one-6-carboxylic acid.

Provenance & Evidence