The reaction of functionalized azomethine ylides as C-unsubstituted nitrile ylide equivalents with acetylenic dipolarophiles is mentioned. Therein, the initially formed cycloadducts, 2,5-dihydropyrroles, by the reaction of the azomethine ylides with substituted acetylenes, undergo a fission reaction to afford 2H-pyrroles and the parent heterocyclic system. Some 2H-pyrroles isomerized to 1H-pyrroles under both thermal and acidic conditions. © 2006.
Kawashima, K., Hiromoto, M., Hayashi, K., Kakehi, A., Shiro, M., & Noguchi, M. (2007). Reaction of functionalized azomethine ylides with acetylenic dipolarophiles: the facile synthesis of functionalized 2H- and 1H-pyrroles. Tetrahedron Letters, 48(6), 941–944. https://doi.org/10.1016/j.tetlet.2006.12.018