反应详情

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.

1. temperaturethe temperature being maintained below 35° C
2. additionare added
3. filtrationare filtered off
4. washwashed with methanol
5. customThe filtrate is evaporated under reduced pressure
6. additionafter addition of 500 ml water
7. extractionextracted 3 times with 150 ml of chloroform
8. dry with materialThe chloroform phases are dried over sodium sulphate
9. customevaporated under reduced pressure
10. customAfter crystallization
11. customfrom 200 ml petrol ether (b.p.: 60°-80° C.) and further recrystallization there