Tandem [8+ 2] Cycloaddition−[2+ 6+ 2] Dehydrogenation Reactions Involving Imidazo [1, 2-a] pyridines and Imidazo [1, 2-a] pyrimidines

M Aginagalde, Y Vara, A Arrieta, R Zangi…

Index: Aginagalde, Maialen; Vara, Yosu; Arrieta, Ana; Zangi, Ronen; Cebolla, Vicente L.; Delgado-Camon, Arantzazu; Cossio, Fernando P. Journal of Organic Chemistry, 2010 , vol. 75, # 9 p. 2776 - 2784

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Citation Number: 45

Abstract

The reaction between benzynes and imidazo [1, 2-a] pyridines (pyrimidines) to form benzo [a] imidazo [5, 1, 2-cd] indolizines and 2, 3, 9c-triazocyclopenta [j, k] fluorenes has been studied computationally and experimentally. It is found that these reactions take place via tandem [π8s+ π2s] and [σ2s+ π6s+ σ2s] processes. The [8+ 2] cycloaddition steps are essentially barrierless, and the aromatization steps occur via highly synchronous aromatic ...