Potassium Carbonate → 2-(4-Benzylpiperidino)-2'-methylpropiophenone

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Reaction Steps

A mixture of 25 g of 2-bromo-2'-methylpropiophenone, 70 ml of dry acetonitrile, 30 g of potassium carbonate and 19 g of 4-benzylpiperidine is stirred for 4 hours at ambient temperature. It is filtered in order to separate off the inorganic residue, and the filtrate is diluted with 200 ml of diethyl ether, which causes precipitation of 4-benzylpiperidine hydrobromide. This is filtered off; the filtrate deposits a second crop of hydrobromide, which is also separated off. The filtrate is then acidified with 300 ml of 3N hydrochloric acid. The intermediate propiophenone hydrochloride is an oil which is insoluble in both phases. The acid aqueous phase is extracted twice with methylene chloride, the extract is washed with water, and aqueous ammonia solution is added. The mixture is stirred and left to separate, the organic phase is dried, filtered and treated with about 100 g of silica in order to retain the traces of 4-benzylpiperidine, the mixture is filtered and the filtrate is evaporated. 10.9 g of an oil are collected.

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