Sodium Hydroxide → 4-Methyl-1-oxo-1,2,3,4-tetrahydropyrazino[1,2-a]indole-7-carboxylic acid

Participants

Reaction Conditions

Reaction Steps

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.

Provenance & Evidence