Sulfuric Acid → 5-methyl-1H,6H,7H,8H-pyrrolo[2,3-g]indazole-7,8-dione

Participants

Reaction Conditions

Reaction Steps

To concentrated sulphuric acid (119 ml) was added portionwise 2-[(E)-hydroxyimino]-N-(5-methyl-1H-indazol-6-yl)-acetamide (34.7 g, 146.3 mmol). The addition was strongly exothermic and the internal temperature was maintained at 70° C. with an ice bath. At the end of the addition the resulting reaction mixture was heated at 80° C. and stirred for 45 min at this temperature. According to LC-MS analysis, the reaction has then reached completion. The reaction mixture was cooled down to ambient temperature. The reaction mixture was poured onto 3.00 kg of ice. The resulting dark-brown suspension was stirred for 30 min and then filtrated. The filter cake was washed extensively with water and dried in vacuo at 55° C. The title product was obtained as a red-brown powder. LC/MS: 202 (M+H)+, 224 (M+H)+.

Provenance & Evidence