Benzene → 3,4,4-Trimethoxy-1-(phenylmethyl)piperidine ethanedioate

To a stirred mixture of 85 parts of 4,4-dimethoxy-1-(phenylmethyl)-3-piperidinol and 480 parts of sodium hydroxide solution 60% were added 288 parts of benzene and 0.5 parts of N,N,N-triethylbenzenemethanaminium chloride. Then there were added dropwise 49.2 parts of dimethyl sulfate at a temperature below 30° C. After stirring overnight at room temperature, there was added another portion of 13.3 parts of dimethyl sulfate and stirring was continued for 4 hours at room temperature. The reaction mixture was cooled, 640 parts of water were added and the layers were separated. The aqueous phase was extracted with benzene. The formed suspension was filtered and the filter-cake was set aside. The combined organic phases were washed with water, dried, filtered and evaporated. The oily residue was distilled (bp. 138° C. at 1 mm. pressure). The distillate was converted into the ethanedioate salt in 2-propanol. The salt was filtered off and crystallized from ethanol, yielding 34.9 parts of 3,4,4-trimethoxy-1-(phenylmethyl)piperidine ethanedioate; mp. 180.6° C. (intermediate 58).

1. stirringstirring
2. waitwas continued for 4 hours at room temperature
3. temperatureThe reaction mixture was cooled
4. customthe layers were separated
5. extractionThe aqueous phase was extracted with benzene
6. filtrationThe formed suspension was filtered
7. washThe combined organic phases were washed with water
8. customdried
9. filtrationfiltered
10. customevaporated
11. distillationThe oily residue was distilled (bp. 138° C. at 1 mm. pressure)
12. filtrationThe salt was filtered off
13. customcrystallized from ethanol

ORD record

ord-99d6d9fea3f240eca07448754c3e1a66

Source dataset

uspto-grants-1990_10

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US04962115