Hydrochloric Acid → 1-[5-(4-Cyclopropanesulfonyl-piperazin-1-yl)pyridin-2-yl]-1,2,3,4-tetrahydroquinoxaline

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Reaction Steps

6.14 g of tert-butyl ester of 4-[5-(4-cyclopropanesulfonyl-piperazin-1-yl)pyridin-2-yl]-3,4-dihydro-2H-quinoxaline-1-carboxylic acid is put in a 1-liter three-necked flask under nitrogen atmosphere. 102 ml of dichloromethane is added, it is cooled in an ice bath and 92 ml of a 4M solution of hydrochloric acid in dioxane is added dropwise. The temperature of the reaction mixture is allowed to return slowly to room temperature and then it is stirred for 5 h. The reaction mixture is diluted with dichloromethane, then cooled in an ice bath. Then a saturated solution of NaHCO3 is added to pH=8. It is decanted and the aqueous phase is extracted with dichloromethane. The water-based organic phases are washed, dried over Na2SO4, filtered on a frit and concentrated. 4.92 g of 1-[5-(4-cyclopropanesulfonyl-piperazin-1-yl)pyridin-2-yl]-1,2,3,4-tetrahydroquinoxaline is obtained in the form of a white solid.

Provenance & Evidence