Yield: 95%

Reaction Conditions:

with phosphorus pentachloride;trichlorophosphate at 125; for 1 h;

Steps:

128 4-chloropyridine-3-sulfonyl chloride
4-chloropyridine-3-sulfonyl chloride
Pentachlorophosphorane (7.29 g, 35 mmol), phosphoryl trichloride (1.86 ml_, 20 mmol) were added to 4-hydroxypyridine-3-sulfonic acid (1.75 g, 10 mmol). The mixture was stirred at 125 °C for 1 h. The solution was allowed to cool to 23 °C and then concentrated to remove excess POCI₃, diluted with Et₂0 and poured onto ice. The residue was stirred for 5 min and then was neutralized with solid NaHC0₃, the mixture was extracted with EtOAc and combined extracts were dried (Na₂S0₄) and concentrated giving 2.02 g (95%) of the title compound. LC-MS m/z 211.8 (M+H)⁺, 0.74 (ret. time).

References:

GLAXOSMITHKLINE INTELLECTUAL PROPERTY DEVELOPMENT LIMITED;ASTEX THERAPEUTICS LIMITED;BOEHM, Jeffrey Charles;DAVIES, Thomas Glanmor;WOOLFORD, Alison Jo-anne;GRIFFITHS-JONES, Charlotte Mary;WILLEMS, Hendrika Maria Gerarda;NORTON, David;SAXTY, Gordon;HEIGHTMAN, Thomas Daniel;LI, Tindy;KERNS, Jeffrey K.;DAVIS, Roderick S.;YAN, Hongxing WO2015/92713, 2015, A1 Location in patent:Page/Page column 299