Hydrochloric Acid → N-ethyl-6,7-dimethoxy-1,2,3,4-tetrahydro-2-naphthylamine hydrochloride

Temperature

-50 °C

A mixture of 7.4 g of anhydrous aluminum chloride and 100 ml of anhydrous methylene chloride was cooled at -50° C. and to the mixture was added dropwise a solution of 5.9 g of 3,4-dimethoxyphenylacetyl chloride and 30 ml of anhydrous methylene chloride. Subsequently, while stirring the solution vigorously, ethylene was forced fed into the solution for 15 minutes. Then, after stirring the solution for 3.5 hours at room temperature (about 25° C.), the reaction solution was cooled in an ice-water bath and 40 ml of water was added dropwise thereto. The methylene chloride layer was washed with a 2 N-HCl aqueous solution, water, a saturated sodium bicarbonate aqueous solution and water in order, dried over anhydrous sodium sulfate and concentrated under reduced pressure to obtain a oily product. To the oily product were added 25 ml of a 19% ethylamine-ethanol solution, 10 ml of absolute ethanol and 0.25 g of platinum oxide, and the solution was catalytically hydrogenated. After take up of hydrogen had been completed, the platinum oxide catalyst was removed by filtration and the filtrate was concentrated under reduced pressure. To the residue obtained was added an ethanolic solution of hydrogen chloride having a concentration of about 18% and then the resulting solution was concentrated under reduced pressure. After adding acetone to the residue, the crystals formed were collected by filtration and dissolved in a 2 N-NaOH aqueous solution. After extraction with chloroform, the chloroform layer was washed with water, dried over anhydrous potassium hydroxide and concentrated under reduced pressure. The residue obtained was purified through alumina column chromatography. To the purified reaction solution was added an ethanolic solution of hydrogen chloride having a concentration of about 18% and the solution was concentrated under reduced pressure to obtain crystals. The crystals were recrystallized from a mixed solution of absolute ethanol and isopropyl alcohol to obtain 1.12 g of N-ethyl-6,7-dimethoxy-1,2,3,4-tetrahydro-2-naphthylamine hydrochloride as colorless needles having a melting point of 246°-248° C. (decomp.).

1. stirringThen, after stirring the solution for 3.5 hours at room temperature (about 25° C.)
2. temperaturethe reaction solution was cooled in an ice-water bath
3. washThe methylene chloride layer was washed with a 2 N-HCl aqueous solution, water
4. dry with materiala saturated sodium bicarbonate aqueous solution and water in order, dried over anhydrous sodium sulfate
5. concentrationconcentrated under reduced pressure
6. customto obtain a oily product
7. customthe platinum oxide catalyst was removed by filtration
8. concentrationthe filtrate was concentrated under reduced pressure
9. customTo the residue obtained
10. concentrationthe resulting solution was concentrated under reduced pressure
11. additionAfter adding acetone to the residue
12. customthe crystals formed
13. filtrationwere collected by filtration
14. dissolutiondissolved in a 2 N-NaOH aqueous solution
15. extractionAfter extraction with chloroform
16. washthe chloroform layer was washed with water
17. dry with materialdried over anhydrous potassium hydroxide
18. concentrationconcentrated under reduced pressure
19. customThe residue obtained
20. customwas purified through alumina column chromatography
21. customTo the purified reaction solution
22. concentrationthe solution was concentrated under reduced pressure
23. customto obtain crystals
24. customThe crystals were recrystallized from a mixed solution of absolute ethanol and isopropyl alcohol

ORD record

ord-2ffa8802115a48f5bed7dab1a9efd64c

Source dataset

uspto-grants-1980_12

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US04239903