Cu-Enabled [3 + 2] Annulation of In Situ Formed Nitrile Ylides with Aryldiazonium Salts: Access to 5-Cyano-1,2,4-Triazoles.

The unified construction of cyano-substituted 1,2,4-triazoles, particularly the 5-cyano counterparts, remains underdeveloped. Herein we describe a three-component method to access a wide range of 1-aryl 5-cyano-1,2,4-triazoles using readily available 2-diazoacetonitriles, nitriles, and aryldiazonium salts. This regiospecific synthesis relies on the dipolar [3 + 2] annulation of the in situ formed nitrile ylides with aryldiazonium salts. Furthermore, this protocol can be amendable to gram-scale synthesis, chemical transformations of the nitrile moieties, and access to chiral bis(cyano-triazole)-1,1'-naphthalene, which would all be likely applicable in the synthesis of structurally diverse bioactive compounds and novel bidentate ligands for asymmetric catalysis.