Visible-Light-Induced Photoredox Catalysis: An Easy Access to Green Radical Chemistry

Abstract

Photoredox catalysis by well-known ruthenium(II) polypyridine complexes and appropriate cyclometalated iridium(III) derivatives is a useful tool for redox reactions in synthetic chemistry, because these materials can effectively catalyze single-electron-transfer (SET) processes by irradiation with visible light. This provides a new strategy for efficient and selective radical reactions. We have developed several photocatalytic reactions in which organic radicals are generated by photoredox catalysis and which have remarkable merits in terms of green and sustainable chemistry.

1 Introduction

2 Photoredox Cycles of [Ru(bpy)₃]²⁺ and Cyclometalated Iridium Complexes

3 Radical Reactions that Occur Through a Reductive Quenching Cycle

3.1 Oxyamination of Enamines

3.2 Tin-Free Giese-Type Reactions Through Oxidation of Organoborates

4 Radical Reactions Through an Oxidative Quenching Cycle

4.1 Two-Electron Transfer Process Mediated by Duroquinone: Oxidative Coupling of an Enamine with a Silyl Enol Ether

4.2 Radical Trifluoromethylation of Alkenes

5 Conclusions and Outlook

Key words

electron transfer - green-chemistry - homogeneous ­catalysis - photochemistry - free radicals - radical reactions

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