1H-indazole-6-sulfonyl chloride(WXC09037) synthesis

Yield:131290-01-2 23%

Reaction Conditions:

Stage #1: 6-amino-1H-indazolewith hydrogenchloride;sodium nitrite in water;acetic acid at -10 - -5; for 0.5 h;
Stage #2: with sulfur dioxide;copper(l) chloride in water;acetic acid at -10 - 20;Inert atmosphere;

Steps:

I-025

A solution of 3.8 g (55 mmol) of NaNU₂ in 5 mL of water is added to 6.7 g (50 mmol) of 6- aminoindazole in 15 mL of concentrated HCl and 5 mL of glacial acetic acid at -10 ⁰C is added at such a rate that the temperature does not exceed -5 ⁰C. After stirring for 30 min, a solution of 1.2 g (13 mmol) of CuCl in 50 mL of saturated SO₂ in acetic acid is added over 10 minutes. The mixture is warmed to rt and stirred until N₂ evolution ceases. The mixture is poured onto ice and the resulting precipitate is filtered, and then is suspended in EtOAc (150 mL) and washed with NaHCCb and brine, dried over MgSO₄, filtered, and concentrated to provide 2.5 g (23%) of 1-025 as a yellow solid.

References:

WO2009/126675,2009,A1 Location in patent:Page/Page column 128