Benzyl Bromide → 4-Benzyl-4-piperidinol

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Reaction Steps

To the Grignard reagent, prepared from 3.6 g of magnesium and 18.9 g of benzyl bromide in 50 ml of diethyl ether, the solution of 18.4 g of 1-benzyl-4-piperidone in 100 ml of diethyl ether is added and the mixture refluxed for one hour. It is decomposed with 30 ml of saturated aqueous ammonium chloride, the ethereal solution separated, dried and evaporated, leaving a thick oil. 26 g thereof are hydrogenated in a mixture of 120 ml of ethanol and 120 ml of acetic acid over 3 g of 10% palladium on carbon at 3 at. and 50° until one molar equivalent of hydrogen has been taken up. It is filtered, the filtrate evaporated, the residue treated with ammonium hydroxide and extracted with methylene chloride. The extract is dried and evaporated, to yield the 4-benzyl-4-hydroxy-piperidine, which is pure enough for further reaction.

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