A Redox‐Active Nickel Complex that Acts as an Electron Mediator in Photochemical Giese Reactions. Issue 15 (6th March 2019)

• Record Type: Journal Article
• Authors: van Leeuwen, Thomas; Buzzetti, Luca; Perego, Luca Alessandro; Melchiorre, Paolo
• Is Part Of: Angewandte Chemie international edition. Volume 58:Issue 15(2019)
• Page Start: 4953
• Page End: 4957
• Publication Date: 2019-03-06
• Subjects: dihydropyridines -- electron mediator -- nickel catalysis -- photochemistry -- synthetic methods; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.201814497
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: We report a simple protocol for the photochemical Giese addition of C(sp 3 )‐centered radicals to a variety of electron‐poor olefins. The chemistry does not require external photoredox catalysts. Instead, it harnesses the excited‐state reactivity of 4‐alkyl‐1, 4‐dihydropyridines (4‐alkyl‐DHPs) to generate alkyl radicals. Crucial for reactivity is the use of a catalytic amount of Ni(bpy)3 2+ (bpy=2, 2′‐bipyridyl), which acts as an electron mediator to facilitate the redox processes involving fleeting and highly reactive intermediates. Abstract : A time to get, and a time to lose electrons : Electron mediators can alleviate limitations associated with the photochemistry of excited‐state intermediates, including short lifetimes and low electron transfer rates. The ability of a nickel complex to act as an electron shuttle assists the excited‐state reactivity of dihydropyridines1 to enable a photochemical Giese addition of C(sp 3 )‐centered radicals to electron‐poor olefins.