Lithium hydroxide, monohydrate → 3,4-dihydro-2H-1,4-benzoxazine-8-carboxylic acid

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Reaction Steps

To a solution of 3,4-dihydro-2H-benzo[b][1,4]oxazine-8-carboxylic acid ethyl ester 2.1 g (10 mmol) of step 3 in a mixture of tetrahydrofuran 10 mL and distilled water 10 mL was added lithium hydroxide monohydrate 0.85 g (20 mmol), followed by stirring at room temperature for 8 hrs. After concentrating the reaction mixture in a vacuum, the reaction mixture was diluted with ethylacetate, washed with 1N HCl and a saturated NaCl solution, and dried over magnesium sulfate. The residue was concentrated in a vacuum and crystallized in ethylacetate/hexane to obtain 1.6 g of the title compound (yield 89%).

Provenance & Evidence