1-(4-Bromo-phenyl)-4-methyl-pent-1-en-3-one → 7-Bromo-1,1-dimethyl-1,2,3,4-tetrahydronaphthalene

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Reaction Steps

To a solution of 1-(4-bromo-phenyl)-4-methyl-pent-1-en-3-one (Compound 14, 7.98 g, 31.7 mmol) in 20 mL diethyl ether at 0° C. was slowly added lithium aluminum hydride (LAH) (1.20 g, 38.0 mmol). After stirring for one hour and subsequent warming to room temperature the reaction was quenched by 2 mL of saturated ammonium chloride solution at 0° C. with an ice bath and dried over anhydrous MgSO4. Solid was removed by filtration and the filtrate was concentrated at reduced pressure to obtain a crude colorless oil. 5 g of polyphosphoric acid (PPA) was then added to the crude oil and the mixture was heated at 120° C. for 15 min. After cooling to room temperature, the mixture was taken up in water (100 mL), extracted with diethyl ether (3×15 mL), washed with brine (1×15 mL), dried (MgSO4) and concentrated at reduced pressure. Purification by flash chromatography (hexane) afforded the title compound (6.70 g, 89% yield) as a light yellow oil:

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