反应详情

温度

75 °C

To a suspension of ethyl ester from step d above (3.2 g, 11.75 mmol) in 100 mL of THF/EtOH (1:1 v/v) was added 1 N aq NaOH (43 mL, 43 mmol). The reaction mixture became a clear solution upon addition of 1 N NaOH. The clear solution was heated at 75° C. for 2 h. The reaction was concentrated and the crude residue was dissolved in water, and extracted with ether. The aqueous layer was acidified to pH ˜4 with 3 N HCl (˜16 mL). A large amount of white precipitate formed which was filtered off and rinsed with cold ether. The wet product was dried in the vacum oven (50° C.) to provide 2.2 g of 4-Methyl-1-oxo-1,2,3,4-tetrahydro-pyrazino[1,2-a]indole-7-carboxylic acid, yield 77% for two steps.

1. concentrationThe reaction was concentrated
2. dissolutionthe crude residue was dissolved in water
3. extractionextracted with ether
4. customA large amount of white precipitate formed which
5. filtrationwas filtered off
6. washrinsed with cold ether
7. customThe wet product was dried in the vacum oven (50° C.)