Thionyl Chloride → 4-(6-fluoro-3-oxo-1,3-dihydro-2H-pyrazolo[4,3-c]cinnolin-2-yl)benzoyl chloride

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Reaction Conditions

Reaction Steps

Crude 4-(6-fluoro-3-oxo-1,3-dihydro-2H-pyrazolo[4,3-c]cinnolin-2-yl)-benzoic acid (1.45 g) from the previous stage was dissolved in thionyl chloride (50 ml). The mixture was heated to 70° C. for 2-3 h until no further gas evolution was observed. The mixture was cooled to room temperature and excess thionyl chloride was removed under vacuum. The residues were azeotroped with toluene (2×20 ml) to give a solid. The solid was collected by filtration, washed with toluene and dried under vacuum. The product was isolated as a yellow powder (670 mg, 1.95 mmol). LCMS: m/z [M+H]+ 339 (methyl ester resulting from sample make-up in methanol).

Provenance & Evidence