Hydrochloric Acid → 3-benzyloxycarbonyl-2,3,4,4a-tetrahydro-1H-pyrazino[1,2-a]quinoxalin-5(6H)-one

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Reaction Steps

To a solution of 13 g. of 4-carbobenzoxy-1-(o-nitrophenyl)piperazine-2-carboxylic acid and 11.0 g. of sodium hydroxide in 200 ml. of water is added a solution of 20 g. of sodium hydrosulfite in 200 ml. of H2O. The orange solution gradually turns colorless over a period of 2-3 hours. Dilute hydrochloric acid is added to bring the pH of the solution to about 3. A white precipitate forms. Stirring is continued for about 3-5 minutes, and the pH is raised to about 7 by the addition of 40% sodium hydroxide. Filtration gives 8.6 g. of product, m.p. 125°-140°. The analytical sample on recrystallization from ethyl acetate hexane gave a m.p. 167°-170°.

Provenance & Evidence