Methanol → 4,4-Dimethoxy-2-[(4-methoxyphenyl)methyl]-1,3,3-trimethylpiperidine

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Reaction Steps

40 ml of borontrifluoride etherate are added drop-wise over 20 minutes and with stirring to a solution of 52.2 g (0.2 Mol) 2-(4-methoxybenzyl)-1,3,3-trimethyl-4-piperidone in 500 ml methanol, the temperature being maintained below 35° C. After stirring for 16 hours at room-temperature 40 g pulverized sodium hydroxide are added. After stirring for a further 30 minutes the obtained sodium salts are filtered off and washed with methanol. The filtrate is evaporated under reduced pressure and after addition of 500 ml water, extracted 3 times with 150 ml of chloroform. The chloroform phases are dried over sodium sulphate and evaporated under reduced pressure. After crystallization from 200 ml petrol ether (b.p.: 60°-80° C.) and further recrystallization there are obtained 25.4 g 4,4-dimethoxy-2-(4-methoxybenzyl)-1,3,3-trimethylpiperidine, m.p.: 91°-92.5° C.

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