1,2-Cyclohexanedione → 3-Benzyl-5,6,7,8-tetrahydroquinoxalin-2(1H)-one

Temperature

-30 °C

A methanol (30 ml) solution of 1,2-cyclohexanedione (13.44 g, 0.12M) was added to phenylalanineamide hydrochloride (20.05 g, 0.1M) dissolved in methanol (200 ml) under cooling below -30° C., and aqueous 12.5N NaOH (20 ml) was added dropwise thereto. The reaction mixture was stirred under -30° C. for 30 mins., whereafter cooling was removed and the mixture was stirred at room temperature for 3 hours. Conc. hydrochloric acid (25 ml) was added to the reaction mixture under ice-cooling, and sodium bicarbonate (15 g) was added after 10 mins. stirring, the methanol then being distilled off in vacuo. The residue, to which was added water, was extracted three times with chloroform, and the extract was washed with water, dried with anhydrous magnesium sulfate and concentrated in vacuo. The residue was washed with acetone and recrystallized from acetone to obtain the product (19.7 g, yield: 82.1%).

1. temperatureunder cooling below -30° C.
2. temperature, whereafter cooling
3. customwas removed
4. stirringthe mixture was stirred at room temperature for 3 hours
5. additionConc. hydrochloric acid (25 ml) was added to the reaction mixture under ice-
6. temperaturecooling
7. additionsodium bicarbonate (15 g) was added after 10 mins
8. stirringstirring
9. distillationthe methanol then being distilled off in vacuo
10. additionThe residue, to which was added water
11. extractionwas extracted three times with chloroform
12. washthe extract was washed with water
13. dry with materialdried with anhydrous magnesium sulfate
14. concentrationconcentrated in vacuo
15. washThe residue was washed with acetone
16. customrecrystallized from acetone

ORD record

ord-1a6b782297504bdeb7904074c08075f6

Source dataset

uspto-grants-1989_10

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US04877877