Trifluoromethanesulfonic acid → 6-bromo-3-methyl-3,4-dihydronaphthalen-1(2H)-one

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Reaction Conditions

Reaction Steps

A flask was charged with trifluoromethane sulfonic acid (450 g, 3 mol) and cooled to 0° C. with an ice-water bath. 4-(3-bromophenyl)-3-methylbutanoic acid, prepared in a similar manner as described in Example 32 (15.5 g, 60 mmol), was added as a solution in DCM (30 mL) slowly to produce a clear dark brown solution. After 15 min, the reaction was diluted with 500 mL of CHCl3 and poured slowly onto approximately 1 L of crushed ice. The resulting slurry was allowed to stir until the solution warms to room temperature and became biphasic. Following separation of layers, the aqueous layer was extracted with CHCl3. The combined organics were washed with brine and dried over anhydrous MgSO4 prior to concentration in vacuo. Purification via Isco column chromatography (50% DCM/hex isocratic) provided a quantitative yield of the named compound as a pale yellow amorphous solid. LCMS-ESI+ (m/z): [M]+ calcd for C11H11BrO: 239.11; found: 239.20.

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