The copper (I)-catalyzed Huisgen dipolar cycloaddition of terminal alkynes 1 with azides 2 [1] to yield 1, 4-and 1, 4, 5-substituted 1, 2, 3-triazoles 3 (azide–alkyne cycloaddition; AAC reaction) has been transformed in recent years, since its description as the prototype “click” reaction,[2] to become a general process with applications in diverse areas ranging from functional materials [3] to biological chemistry.[4, 5] The generally accepted mechanism ...