Visible light is an abundant source of energy. While the conversion of light energy into electrical energy (photovoltaics) is highly developed and commercialized, the use of visible light in chemical synthesis is far less explored. Chemical photocatalysts that mimic principles of biological photosynthesis utilize visible light to drive endothermic or kinetically hindered reactions. This work summarizes in 16 chapters the state of the art and the challenges of this emerging future technology.

Burkhard König, University of Regensburg, Germany.

1;List of contributing authors;5 2;1 Introduction;15 3;2 Early pioneers of organic photochemistry;17 3.1;2.1 References;29 4;3 Photophysics of Photocatalysts;33 4.1;3.1 Setting the Frame;35 4.2;3.2 The Experimentalist's Perspective;38 4.3;3.3 The Theoreticians' Perspective: A Closer Look;45 4.3.1;3.3.1 Transition probabilities;46 4.3.2;3.3.2 Orbitals;50 4.4;3.4 References;57 5;4 Flavin photocatalysis;59 5.1;4.1 Introduction;59 5.1.1;4.1.1 General properties;60 5.2;4.2 Early examples of flavin photocatalysis;62 5.3;4.3 Flavin photocatalysis in synthesis application;65 5.4;4.4 Flavin-related compounds in photocatalysis;72 5.5;4.5 Photooxidations via singlet oxygen mechanism;73 5.6;4.6 Conclusion;75 5.7;4.7 References;75 6;5 Templated Enantioselective Photocatalysis;81 6.1;5.1 Introduction;81 6.2;5.2 Early studies. Paternò-Büchi cycloadditions of a chiral aromatic aldehyde and cyclic enamines;83 6.3;5.3 Enantioselective Norrish-Yang cyclization reaction of prochiral imidazolidinones;83 6.4;5.4 Enantioselective photochemical [4+4]-cycloadditions and electrocyclic [4p]-ring closure of 2-pyridones;85 6.5;5.5 Enantioselective [6p]-photocyclization of acrylanilides;86 6.6;5.6 Enantioselective Diels-Alder reaction of a photochemically generated ortho-quinodimethane;87 6.7;5.7 Formal [3+2]-photocycloadditions of 2-substituted naphthoquinones;88 6.8;5.8 Intramolecular [2+2]-photocycloadditions of substituted 5,6-dihydro-1H-pyridin-2-ones;88 6.9;5.9 Enantioselective radical cyclizations;89 6.9.1;5.9.1 Reductive radical cyclization reactions of 3-(.-iodoalkylidene)-piperidin-2-ones;89 6.9.2;5.9.2 Reductive radical cyclization of 3-(3-iodopropoxy)propenoic acid derivatives;90 6.9.3;5.9.3 Radical cyclization reactions of 4-substituted quinolones;91 6.10;5.10 [2+2]-Photocycloaddition reactions of substituted isoquinolones;91 6.11;5.11 [2+2]-Photocycloaddition reactions of substituted quinolones;93 6.11.1;5.11.1 Intermolecular [2+2]-photocycloaddition reactions of quinolones;93 6.11.2;5.11.2 Intramolecular [2+2]-photocycloadditions of 4-(2?-aminoethyl)quinolones;93 6.11.3;5.11.3 Intramolecular [2+2]-photocycloadditions of 4-(?-alkenyloxy)-quinol-2-ones;95 6.12;5.12 Light-induced enantioselective catalysis;96 6.12.1;5.12.1 Photoinduced electron transfer enantioselective catalytic reactions;98 6.12.2;5.12.2 Catalyzed enantioselective [2+2]-photocycloadditions of 4-substituted quinolones;98 6.13;5.13 Conclusion;100 6.14;5.14 References;100 7;6 Photocatalysis with nucleic acids and peptides;105 7.1;6.1 Introduction;105 7.2;6.2 DNA-assisted enantioselective reactions;105 7.2.1;6.2.1 Photocatalytically active DNA (PhotoDNAzymes);107 7.2.2;6.2.2 Benzophenone as photosensitizer in DNA for the development of PhotoDNAzymes;108 7.3;6.3 Small peptides as organocatalysts;112 7.3.1;6.3.1 Development of peptides for photocatalytic addition to olefins;115 7.4;6.4 Conclusion;121 7.5;6.5 References;121 8;7 Visible light photoredox catalysis with [Ru(bpy)3]2+: General principles and the twentieth century roots;125 8.1;7.1 Introduction;125 8.2;7.2 [Ru(bpy)3]2+ and its photoredox properties;125 8.3;7.3 Application of [Ru(bpyb]2+ as catalyst in the twentieth century;127 8.4;7.4 Conclusion;143 8.5;7.5 Abbreviations;145 8.6;7.6 References;145 9;8 Homogeneous visible light-mediated transition metal photoredox catalysis other than ruthenium and iridium;153 9.1;8.1 Introduction;153 9.2;8.2 Copper in visible light catalysis;153 9.3;8.3 Rhenium and platinum in visible light catalysis;157 9.4;8.4 Iron in visible light catalysis;159 9.4.1;8.4.1 Photocatalytic oxidation of hydrocarbons;159 9.4.2;8.4.2 Photocatalytic oxidative decarboxylation;159 9.4.3;8.4.3 Oxidative degradation;160 9.4.4;8.4.4 Isomerization;162 9.5;8.5 Conclusion;163 9.6;8.6 References;163 10;9 Synergistic Visible Light Photoredox Catalysis;165 10.1;9.1 Introduction;165 10.2;9.2 Stabilized iminium ions;167 10.2.1;9.2.1 Secondary amine-catalyzed Mannich reactions;168 10.2.2;9.2.2 Coinage metal-catalyzed alky