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

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