Recent Advances in Cycloaddition Reactions with Alkynes to Construct Heterocycles

Abstract

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 Introduction2 Intermolecular Cycloaddition To Construct Azepine Derivatives2.1 [5+2] Cycloaddition2.2 [3+2+2] Cycloaddition2.3 [3+2]/[5+2] Cycloaddition3 Intermolecular [4+2] Cycloaddition To Construct Isoquinolines or Isocoumarins4 Intermolecular [3+2] Cycloaddition To Construct Spirohetero­cyclic Compounds, Indoles, Furans, and Pyrroles5 Summary and Outlook

Ligand-Enabled Palladium-Catalyzed [3 + 2] Annulation of Aryl Iodides with Maleimides via C(sp3)–H Activation

“…Transition-metal-catalyzed annulation reactions via C–H bond activation have emerged as robust methods for the synthesis of cyclic compounds. Numerous reactions of this type have been extensively investigated and developed . Notably, the Yu group reported a highly elegant Pd-catalyzed [3 + 2] annulation of aliphatic amides with maleimides via twofold C­(sp 3 )–H activation in 2020 (Scheme A) .…”