Take Advantage of the N‐Nucleophilicity of Imine in Catalytic Cyclization Reactions

Abstract Imines, or Schiff bases are basic and important synthons in modern chemical synthesis, which are widely used in methodological studies, synthesis of natural products or pharmaceutical agents, construction of organic porous materials and relative late‐stage modifications. In most cases, the imines often act as “electrophilic reagents” in reactions on the basis of their C‐electrophilicity owing to the dipole effect of the C=N bond. However, on the other hand, reactions initiated by the N‐nucleophilicity of imine, draw relatively less attentions. In this concept article, we try to give a concise summary of the reactions, especially the cyclization reaction that are initiated by the N‐nucleophilicity of imine. The basic measurement data and discussions of the N‐nucleophilicity of different imines, relative possible mechanisms, catalytic strategies, and reaction types in this context are briefly discussed. We hope the imines, as one of the basic chemical synthons in organic synthesis, will be utilized in broader scope in the future by taking advantage of their N‐nucleophilicity.