Bromide ion → 1,1-Diphenyl-hex-5-en-2-ol

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Reaction Steps

A dry three-neck, round-bottom flask fitted with a reflux condensor, air-balance drop funnel and nitrogen inlet was charged with Mg (0.11 g, 4.44 mmol) and a crystal of I2. The flask was warmed (heat gun) to volatilize the I2 under vacuum, and then was allowed to cool. Dry ethyl ether (10 ml) was added next followed by introduction of catalytic neat 4-bromo-1-butene (0.02 g). The reaction was initiated by brief warming and then the rest of total amount of bromide (0.4 g, 2.96 mmol) in dry ethyl ether (5 ml) was added dropwise over 5 minutes. The mixture was refluxed for 30 minutes and then was allowed to reach 0° C. Into the stirred Grignard reagent solution was added dropwise a solution of diphenylacetaldehyde 1 (0.64 g, 3.26 mmol) in dry ethyl ether (5 ml), and the reaction mixture was stirred for an additional 3.5 hr at room temperature. Saturated aqueous NaHCO3 was added to the reaction mixture at 0° C., the organic phase was separated and the aqueous phase was extracted with ethyl ether (3×20 ml). The combined organic phases were washed with brine and water, then dried over anhydrous Na2SO4. The solvent was removed under reduced pressure, and flash chromatography of the crude residue (SiO2, hexane/Ethyl Acetate 9:1) gave 1,1-diphenyl-hex-5-en-2-ol 8 (0.68 g, 91%) as a liquid.

Provenance & Evidence