Panchaud, Philippe published the artcile3-Pyridinesulfonyl azide: A useful reagent for radical azidation, Name: Pyridine-3-sulfonic acid, the publication is Advanced Synthesis & Catalysis (2004), 346(8), 925-928, database is CAplus.
Radical azidations and carboazidations have been achieved using 3-pyridinesulfonyl azide as azidating agent. Due to its base properties and its polarity, the excess of reagent is readily removed at the end of the reaction by filtration through silica gel or by extraction with either aqueous 1M HCl or 1M CuSO4. The use of this reagent greatly facilitates the tedious purifications of the final azides frequently encountered when reactions are run according to the original procedure involving benzenesulfonyl azide. Thus, reaction of Et 2-iodoacetate with 1-octene in presence of Bu6Sn2/di-tert-Bu hyponitrite/3-pyridinesulfonyl azide in C6H6 gave 80% Et 4-azidodecanoate.
Advanced Synthesis & Catalysis published new progress about 636-73-7. 636-73-7 belongs to pyridine-derivatives, auxiliary class Pyridine,Sulfonic acid, name is Pyridine-3-sulfonic acid, and the molecular formula is C5H5NO3S, Name: Pyridine-3-sulfonic acid.
Referemce:
https://en.wikipedia.org/wiki/Pyridine,
Pyridine | C5H5N – PubChem