Water → 2-(4-Chlorophenyl)-5-cyclopropyl-6-nitro-2H-indazole-3-carboxylic acid

Participants

Reaction Conditions

Reaction Steps

To a stirred solution of (v) (20 g, 0.06 mol) in EtOH:water (400 ml, 1:1 v/v) was added NaOH (59.0 g, 0.02 mol) and the reaction mixture heated at 90° C. for 15 h. The reaction was then cooled to RT and the volatiles were removed in vacuo. The residual aqueous solution was acidified to pH 2 with aq. 2N HCl solution whereupon a solid precipitated from solution. The solid was separated by filtration and dissolved in EtOAc (300 mL), dried (Na2SO4) and concentrated in vacuo to give (vi) (7.5 g, with purity 75% by HPLC analysis). The material was used unpurified in subsequent steps.

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