Sulfuric Acid → 4-Bromo-2,2-dimethyl-2,3-dihydrobenzofuran

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A stirred solution of 12.3 grams (0.051 mole) of 7-amino-4-bromo-2,3-dihydro-2,2-dimethylbenzofuran and 30 mL of toluene in 200 mL of ethanol is cooled in an ice-bath, and 5.6 mL (0.102 mole) of concentrated sulfuric acid is added slowly, followed by 5.6 grams (0.082 mole) of sodium nitrite. Upon completion of addition, the ice-bath is removed, and the reaction mixture is warmed to 50° C. The reaction mixture temperature is then brought to about 75° C., where it is stirred for 30 minutes. After this time the reaction mixture is heated at reflux for one hour and then is poured into 200 mL of water. The mixture is extracted with two 150 mL portions of diethyl ether. The combined extracts are tided with magnesium sulfate and filtered. The filtrate is concentrated under reduced pressure to a residual oil. The oil is subjected to column chromatography on silica gel. Elution is accomplished using petroleum ether. The product-containing fractions are combined and concentrated under reduced pressure, yielding 3.6 grams of 4-bromo-2,3-dihydro-2,2-dimethylbenzofuran. The NMR spectrum is consistent with the proposed structure. Step C Synthesis of 4-bromo-2,3-dihydro-2,2-dimethyl-3-benzofuranone as an intermediate

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