反应详情

A stirred solution of 4-(4-benzylpiperazin-1-yl)-2-[(phenylsulfonyl)methyl]-aniline (0.371 g, 0.88 mmol) in 4.0 M aqueous hydrochloric acid is cooled in an ice bath, treated dropwise with NaNO2 (91 mg, 1.32 mmol) in water, stirred for 40 min, treated with 2.5 M aqueous NaOH to pH ˜14 and filtered. The filtercake is dissolved in CH2Cl2, and chromatographed (silica gel, ethyl acetate as eluent) to afford the free indazole of the title product as a yellow solid (276 mg, 64%). The solid is dissolved in a mixture of ethanol and CH2Cl2, treated with 4.0 M HCl in dioxane, and concentrated in vacuo to give a solid residue. The residue is triturated with ethyl acetate to afford the title product as an off-white solid, 278 mg (57% yield), mp 177–180° C., identified by NMR and mass spectral analyses.

1. filtrationfiltered
2. dissolutionThe filtercake is dissolved in CH2Cl2
3. customchromatographed (silica gel, ethyl acetate as eluent)