文摘
Silver-mediated isocyanide-alkyne [3 + 2] cycloaddition has been developed as a new method for the synthesis of pyrroles. Density functional theory (DFT) calculations toward this reaction reveal that terminal alkynes participated cycloadditions proceed through two successive 1,5-silver migrations, in which the silver migrates between two carbon atoms and finally returns to original carbon. Natural population analysis (NPA) indicates that silver migration guides the move of charge into a rational way, thereby facilitating the cycloaddition. An analogous silver-migration mechanism is also suitable to explain the reactivity of the cycloaddition between isocyanide and internal alkynes, which shows the generality of the silver-migration process. Moreover, competitive experiments are consistent with the computational results, which provides further support for the mechanism.