Hydrochloric Acid → 3,4-dihydro-4-(2-hydroxy-2-phenylethyl)-2,2-dimethyl-6-nitro-2H-1,4-benzoxazine

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Reaction Conditions

Reaction Steps

In an argon gas stream, 1.5 g of 3,4-dihydro-2,2-dimethyl-6-nitro-3-oxo-4-phenacyl-2H-1,4-benzoxazine was added to 30 ml of a 1.0 M solution of borane in tetrahydrofuran at 0°-10° C. The above solution was stirred at 70° C. for 1 hour, at the end of which time 5.6 ml of methanol was gradually added. After stirring at 70° C. for 15 minutes, 5.6 ml of concentrated hydrochloric acid was added and the mixture was further stirred at 70° C. for 1 hour. The solvent was then distilled off and the residue was diluted with 30 ml of water, made alkaline with potassium carbonate, and extracted with ethyl acetate. The extract was dried over anhydrous magnesium sulfate and the solvent was distilled off. The residue was purified by silica gel column chromatography (eluent: ethyl acetate-n-hexane) to give 1.67 g of 3,4-dihydro-4-(2-hydroxy-2-phenylethyl)-2,2-dimethyl-6-nitro-2H- 1,4-benzoxazine as oil.

Provenance & Evidence