Water → 5-Chloro-3,4-dihydroquinoxalin-2(1H)-one

Participants

Reaction Steps

4-tert-Butyl-5-chloro-3,4-dihydro-1H-quinoxalin-2-one from Example 12C (1.5 g, 6.1 mmol) was suspended in 2N sulphuric acid (45 ml) and stirred for 18 h. The mixture was filtered and the filtrate was neutralised with sodium hydrogen carbonate, extracted with EtOAc, dried and evaporated. The residue was taken up in ethanol (30 ml) and cooled in an ice/water bath. Sodium borohydride (460 mg, 12 mmol) was added and the mixture was allowed to warm to room temperature over 2 h. Water (1 ml) was added and the mixture was evaporated. The residue was triturated with ice-cold water, filtered, washed with ice-cold water and dried in vacuo over phosphorous pentoxide to give an orange solid; yield 550 mg, 49%.

Provenance & Evidence