Synthesis of mesomeric betaines containing a pyrrolo- or imidazotriaziniumolate system and their cycloaddition with acetylenic dipolarophiles leading to triazocinone derivatives
containing a cyclic azomethine imine unit were synthesized and their cycloaddition with acetylenic dipolarophiles were examined. Unexpectedly the cycloaddition of the betaines with electron-deficient dipolarophiles gave ring-expanding adducts having a triazocinone structure. With electron-rich dipolarophiles such as ynamines, the reactions proceeded more readily leading regioselectively to the same type of triazocinones