Visible-Light-Promoted and Photoredox-Catalyzed Radical Addition to Triple Bonds

Abstract

This account details a series of visible-light-promoted and photoredox-catalyzed radical additions to triple bonds, including those of isocyanides, alkynes, cyanides and carbon monoxide. 6-Substituted phenanthridines, 1-substituted isoquinolines and ortho-substituted pyridine derivatives are synthesized via radical addition to isocyanides. A number of (hetero)aromatic compounds are prepared by the addition of radicals to alkynes. Carbonyl compounds can be easily obtained by radical addition to carbon monoxide. Tetracyclic quinazolinones are constructed by radical addition to cyanides. Furthermore, a wide range of quinoline and quinoxaline derivatives are synthesized by way of domino radical isocyanide/alkyne insertions and isocyanide/cyanide insertions, respectively. All the reactions can be carried out in high yields under mild conditions. 1 Introduction 2 Synthesis of Six-Membered Heteroaromatic Rings by Radical Addition to Isocyanides 2.1 Synthesis of 6-Substituted Phenanthridines 2.2 Synthesis of 1-Substituted Isoquinolines 2.3 Synthesis of ortho-Substituted Pyridines 3 Synthesis of (Hetero)aromatic Compounds by Radical Addition to Alkynes 3.1 Synthesis of Six-Membered (Hetero)aromatic Compounds 3.2 Synthesis of Five-Membered (Hetero)aromatic Compounds 4 Synthesis of Carbonyl Compounds by Radical Addition to Carbon Monoxide 5 Synthesis of Tetracyclic Quinazolinones by Radical Addition to Cyanides 6 Synthesis of Quinolines by Domino Radical Isocyanide/Alkyne Insertions 7 Synthesis of Quinoxalines by Domino Radical Isocyanide/Cyanide Insertions 8 Conclusions and Outlook