Copper-Catalyzed Azomethine Imine–Alkyne Cycloadditions (CuAIAC)

Although the first example of copper-catalyzed azomethine imine–alkyne cycloaddition (CuAIAC) was published only a year after the seminal papers of Meldal and Sharpless on Cu-catalyzed azide–alkyne cycloaddition (CuAAC), the CuAIAC reaction has remained overlooked by the synthetic community for almost a decade. Since 2010, however, CuAIAC reaction started to emerge as a promising supplement to the well-known CuAAC reaction. The present review surveys primarily the literature on CuAIAC reaction since 2003. Beside this, azomethine imine–alkyne cycloadditions catalyzed by other metals, selected examples of metal-free reactions, and related [3+3] and [3+4] cycloadditions of azomethine imines are presented. All these experimental data indicate the viability of CuAIAC in organic synthesis and the applicability in ‘click’ chemistry. 1 Introduction 2 Reactions with Acyclic Azomethine Imines 3 Reactions with C,N-Cyclic Azomethine Imines 4 Reactions with N,N-Cyclic Azomethine Imines 5 Reactions with C,N,N-Cyclic Azomethine Imines 6 The Mechanism of the CuAIAC Reaction 7 Conclusions and Outlook