Hydrogen Bromide → 6-Bromo-1,3-dihydro-2-benzofuran-1-one

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Reaction Conditions

Reaction Steps

6-Amino-1(3H)-isobenzofuranone (3.0 g, 20 mmol) obtained from Example 26-(1) was dissolved in a mixture of 47% aqueous hydrobromic acid solution (15 ml) and water (15 ml), then the mixture was cooled to 0° C., and a solution of sodium nitrite (1.45 g, 21 mmol) in water (7 ml) was slowly added thereto. Further, a solution of copper (I) bromide (3.6 g, 25 mmol) dissolved in 47% aqueous hydrobromic acid solution (10 ml) was added to the reaction mixture, and the resulting mixture was stirred at 80° C. for 20 minutes. After cooling the mixture, the liberated product was collected by filtration and then washed with water. The obtained pale brown solid was dissolved in ethyl acetate, then the insoluble material was removed by filtration, and the filtrate was washed successively with a 1N aqueous solution of hydrochloric acid, an aqueous solution of sodium hydrogen carbonate, and an aqueous solution of sodium chloride, and then dried over anhydrous magnesium sulfate. After filtration, the filtrate was concentrated to afford the title compound (3.57 g, 84% yield) as a crystalline solid.

Provenance & Evidence