2-Bromopropane → 7-Isopropoxy-3,4-dihydronaphthalen-1(2H)-one

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Reaction Steps

A suspension of 24.3 g (0.22 mole) of potassium tert-butoxide in 240 ml of dimethyl sulfoxide under a nitrogen atmosphere was stirred and cooled in a cold water bath while a solution of 29.2 g (0.18 mole) of 3,4-dihydro-7-hydroxy-1(2H)-naphthalenone in 400 ml of dimethyl sulfoxide was added dropwise over 45 minutes. The mixture was stirred at room temperature for an additional 45 minutes, and then 23.7 ml (31.0 g; 0.25 mole) of 2-bromopropane was added in one portion. After stirring for an additional 30 hours, the mixture was added to 2.0 kg of ice/water and extracted with dichloromethane (4×300 ml). The combined organic layers were back-washed with water (2×150 ml), dried (anhydrous magnesium sulfate), and evaporated (vacuum) to an oil residue. Flash chromatographic purification (silica gel, dichloromethane elution) of the residue yielded 24.0 g (65% yield) of the analytically pure ether product as an oil, suitable for conversion to the naphthol described in Example 4.

Provenance & Evidence