3-Pyridinesulfonyl azide is a highly efficient reagent for radical azidation. 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. Carboazidation reactions can be run under tin-free conditions in water using triethylborane as an initiator.

This work was carried out in the group of Prof. Philippe Renaud.

References:

• P. Panchaud, P. Renaud;
  "3-Pyridinesulfonyl Azide: A Useful Reagent for Radical Azidation"
  Adv. Synth. Catal., 346, 925-928, (2004); doi:10.1002/adsc.200404038.