7-fluoro-3,4-dihydro-2H-1,4-benzoxazin-3-one → 7-Fluoro-3,4-dihydro-2H-1,4-benzoxazine

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Reaction Steps

3-Oxo-7-fluoro-3,4-dihydro-2H-benzo[b][1,4]oxazine (2.2 g, 1 eq, 13.1 mmol) obtained in step (ii) in dry THF (10 ml) was added drop wise to a refluxing THF (60 ml) containing LAH (1.5 g, 3 eq, 39.5 mmol). It was further refluxed for 3 h and quenched with ethyl acetate. To this water (1.5 ml), 15% sodium hydroxide (1.5 ml) and water (4.5 ml) were added sequentially. Once Al(OH)3.H2O precipitated out, it was filtered though celite. The filtrate was condensed on rotavapour and chromatographed (ethyl acetate and hexane) to yield 7-fluoro-3,4-dihydro-2H-benzo[b][1,4]oxazine (1.3 g, yield 65%) as yellow oil.

Provenance & Evidence