Palladium(II)-Catalyzed Redox-Neutral Cyclizations of Alkynes Containing Alkenyl or Electrophilic Functional Groups: A Convenient Synthesis of Carbocycles and Heterocycles

The palladium(II)-catalyzed redox-neutral cyclizations of alkynes bearing alkenyl or electrophilic functional groups, such as carbonyl, imino, or cyano groups, were developed to provide convenient approaches to various carbocycles and heterocycles. These tandem reactions are initiated by nucleopalladation of alkynes, transmetalation of arylboron reagents with palladium, or hydropalladation of alkynes, and they are quenched by β-heteroatom elimination, addition to electron-deficient alkenes, or addition to carbon–heteroatom multiple bonds. This account reviews these types of reaction, with a focus on our contributions to the field. 1 Introduction 2 Tandem Reactions of Functionalized Alkynes Initiated by Nucleo­palladation 3 Tandem Reactions Of Functionalized Alkynes Initiated by Transmetalation of Palladium(Ii) with Arylboron Reagents 4 Tandem Reactions of Functionalized Alkynes Initiated by Hydro­palladation 5 Conclusion