Selective Synthesis and Cycloaddition Reactions of New Azomethine Imines Containing a 1,2,4‐Triazine Ring

Abstract

AbstractThe reactions of 4,5‐dihydro[1,2,4]triazolo[3,4‐c]benzo[1,2,4]triazines with aromatic aldehydes gave stable iminium salts which were deprotonated to give new azomethine imines. These new mesomeric betaines underwent 1,3‐dipolar cyclization reactions to yield new tetra‐ and pentacyclic heterocycles. X‐ray analysis and decoupling NMR experiments unambiguously supported the fact that these transformations are regioselective and that the iminium moieties were formed at the N‐5 atom in each case. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)