Hydrochloric Acid → 4-Ethyl-2-(p-methoxybenzyl)-1,3,3-trimethyl-4-piperidinol hydrochloride

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Reaction Steps

The hydrochloride (18 g) of 2-(p-methoxybenzyl)-1,3,3-trimethyl-4-piperidone is converted to the free base by shaking with ether and aqueous sodium hydroxide, followed by evaporation of the ethereal solution. The oily base is dissolved in 30 ml of absolute ether and subsequently reacted with ethyl lithium (3.6 g in 300 ml of benzene) under conditions as described in example 39. According to gaschromatographic examination, conversion to the piperidinol occurs to the extent of only 25 percent. After the addition of water the reaction mixture is worked up as described in example 39 and the crude mixture of piperidone and piperidonal so obtained is treated again with ethyl lithium (2.7 g in 250 ml of benzene). This procedure is repeated once more whereafter still 20 percent of the piperidone appears to be present. Processing as usually furnishes 19 g of an oily base, which is converted to the hydrochloride with the aid of ethanolic hydrogen chloride. After the addition of acetone and ether, 9 g of the above crystalline product separates. Yield 45%. Melting point 232 -234° C with decomposition.

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