DBU-Catalyzed [3+3] and [3+2] Annulation Reactions of Azomethine Ylides with -Diazocarbonyls as N-Terminal Electrophiles: Modular, Atom-Economical Access to 1,2,4-Triazine and 1,2,4-Triazole Derivatives

The DBU-catalyzed [3+3] and [3+2] cyclization reactions of azomethine ylides with -diazocarbonyls as N-terminal electrophiles have been developed. These reactions involve a sequential intermolecular nucleophilic addition/intramolecular cyclization/oxidation procedure. By the assembly of readily available starting materials, these transformations offer novel, highly efficient one-pot syntheses of various functionalized 1,2,4-triazine and 1,2,4-triazole derivatives in an atom-economical manner under ambient and metal-free conditions in a high regio- and diastereoselective manner.