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

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Reaction Steps

Thionyl chloride (90 ml) was added to 4-(3-oxo-1,3-dihydro-2H-pyrazolo-[4,3-c]cinnolin-2-yl)benzoic acid (2.36 g, 7.70 mmol). The mixture was heated to reflux for 2 h under nitrogen atmosphere. A dark red solution was obtained, cooled to room temperature and excess thionyl chloride was removed under vacuum. Toluene (30 ml) was added to the residues and the mixture was stirred at room temperature under nitrogen atmosphere until precipitation was complete. The solids were collected by filtration and washed with toluene (2×30 ml). The title compound was isolated as a red solid (2.20 g, 6.77 mmol, 88%) LCMS: m/z 321 [M+H]+ (methyl ester resulting from sample make-up in methanol).

Provenance & Evidence