Recent Advances in Cycloaddition Reactions with Alkynes to Construct Heterocycles

Heterocyclic compounds, especially N-heterocycles and O-heterocycles, are prominent structural motifs present in numerous natural products and medically and/or economically important compounds. This review aims to describe the development of transition-metal-catalyzed cycloaddition reactions of functionalized m-atom partners with alkynes to access a wide range of five-, six-, and seven-membered heterocycles, that is functionalized N-heterocycles and O-heterocycles such as azepines, isoquinolines, isocoumarins, spiroheterocycles, indoles, furans, and pyrroles, in a selectively controlled manner with an emphasis on scope and limitations and with a discussion of the mechanisms. 1 Introduction 2 Intermolecular Cycloaddition To Construct Azepine Derivatives 2.1 [5+2] Cycloaddition 2.2 [3+2+2] Cycloaddition 2.3 [3+2]/[5+2] Cycloaddition 3 Intermolecular [4+2] Cycloaddition To Construct Isoquinolines or Isocoumarins 4 Intermolecular [3+2] Cycloaddition To Construct Spirohetero­cyclic Compounds, Indoles, Furans, and Pyrroles 5 Summary and Outlook