Development of a Safe and Efficient Alkyl Azide Synthesis using Arylsulfonyl Azide

Abstract

Sodium azide has traditionally been used as the source of azide anion for the synthesis of alkyl azides. Besides difficulties with solubility, sodium azide is toxic, can be absorbed through the skin, and forms potentially explosive compounds with H₂O, Brønsted acids, CH₂Cl₂, and CHCl₃. To avoid these dangers, a new azide transfer reagent was developed from the reaction of 4-acetamidobenzenesulfonyl azide (p-ABSA) and 1,8-diazabicyclo[5.4.0]-undec-7-ene (DBU). It is much safer than sodium azide and was used for the synthesis of alkyl and acyl azides. Alkyl azides thus obtained were employed in an attempted in situ generation of 1,2,3-triazoles, which are aromatic five-membered ring heterocycles having two carbon atoms and three nitrogen atoms, and are biologically important. A known one-pot procedure for 1,2,3-triazole synthesis, described by Fokin and colleagues, was repeated and the formation and ease of isolation of the triazole products was compared with the new chemistry described herein.