Osmapyridine and Osmapyridinium from a Formal [4+2] Cycloaddition Reaction

摘要

As one of the most important cycloaddition reactions, the Diels-Alder reaction is widely used in modern organic synthesis [Eq. (1)]. In contrast, hetero-Diels-Alder reactions using nitriles as the dienophile [Eq. (2)] remain relatively rare. Recently, the activation of 1,3-dienes by organolithium reagents was reported, and their formal [4+2] reaction with nitriles becomes feasible. To the best of our knowledge, however, the [4+2] cycloaddition reaction between 1-metalla-1,3-dienes and nitriles has not been reported [Eq. (3)].