Visible-Light Photoredox Catalyzed Double C–H Functionalization: Radical Cascade Cyclization of Ethers with Benzimidazole-Based Cyanamides
Si Jiang, Xiao-Jing Tian, Shuyao Feng, Jiang‐Sheng Li, Zhiwei Li, Cui‐Hong Lu, Chao‐Jun Li, Weidong Liu
Abstract
A visible-light photoredox catalyzed radical cascade cyclization of simple ethers with cyanamides is developed at room temperature. This strategy involves sequential inert Csp3-H/Csp2-H functionalizations through intermolecular addition reaction of oxyalkyl radicals to N-cyano groups followed by radical cyclization of iminyl radicals in situ generated with C-2 aryl rings. This method allows for efficient synthesis of tetracyclic benzo[4,5]imidazo[1,2-c]quinazolines. Importantly, this is the first example of an intermolecular–intramolecular radical cascade cyclization reaction of cyanamides.
Topics & Concepts
ChemistryRadicalIntermolecular forcePhotoredox catalysisBenzimidazoleIntramolecular forceCascadeRadical cyclizationPhotochemistryCatalysisArylSurface modificationInertCombinatorial chemistryPhotocatalysisOrganic chemistryMoleculeAlkylChromatographyPhysical chemistryCatalytic C–H Functionalization MethodsRadical Photochemical ReactionsSulfur-Based Synthesis Techniques