A fundamental aim in the field of catalysis is the development of new modes of small molecule activation. One approach toward the catalytic activation of organic molecules that has received much attention recently is visible light photoredox catalysis. In a general sense, this approach relies on the ability of metal complexes and organic dyes to engage in single-electron-transfer (SET) processes with organic substrates upon photoexcitation with visible light.

Many of the most commonly employed visible light photocatalysts are polypyridyl complexes of ruthenium and iridium, and are typified by the complex tris(2,2′-bipyridine) ruthenium(II), or Ru(bpy)32+ (Figure 1). These complexes absorb light in the visible region of the electromagnetic spectrum to give stable, long-lived photoexcited states.1,2 The lifetime of the excited species is sufficiently long (1100 ns for Ru(bpy)32+) that it may engage in bimolecular electron-transfer reactions in competition with deactivation pathways.3 Although these species are poor single-electron oxidants and reductants in the ground state, excitation of an electron affords excited states that are very potent single-electron-transfer reagents. Importantly, the conversion of these bench stable, benign catalysts to redox-active species upon irradiation with simple household lightbulbs represents a remarkably chemoselective trigger to induce unique and valuable catalytic processes.






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Figure 1


Ruthenium polypyridyl complexes: versatile visible light photocatalysts.

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Visible Light Photoredox Catalysis with Transition Metal Complexes: Applications in Organic Synthesis

Multicomponent reactions (MCRs) are fundamentally different from two-component reactions in several aspects. Among the MCRs, those with isocyanides have developed into popular organic-chemical reactions in the pharmaceutical industry for the preparation of compound libraries of low-molecular druglike compounds. With a small set of starting materials, very large libraries can be built up within a short time, which can then be used for research on medicinal substances. Due to the intensive research of the last few years, many new backbone types have become accessible. MCRs are also increasingly being employed in the total synthesis of natural products. MCRs and especially MCRs with isocyanides offer many opportunities to attain new reactions and basic structures. However, this requires that the chemist learns the “language” of MCRs, something that this review wishes to stimulate.

Multicomponent Reactions with Isocyanides.

3.7. Palladium Nanoparticles as Catalysts 888 3.8. Other Transition-Metal Complexes 888 3.9. Transition-Metal-Free Reactions 889 4. Applications 889 4.1. Alkynylation of Arenes 889 4.2. Alkynylation of Heterocycles 891 4.3. Synthesis of Enynes and Enediynes 894 4.4. Synthesis of Ynones 896 4.5. Synthesis of Carbocyclic Systems 897 4.6. Synthesis of Heterocyclic Systems 898 4.7. Synthesis of Natural Products 903 4.8. Synthesis of Electronic and Electrooptical Molecules 906

https://www.chem.ccu.edu.tw/~joyce/referance/ericyang/Chem.%20Rev/Chem.%20Rev.%202007,%20107,%20874-922.pdf

The Sonogashira Reaction: A Booming Methodology in Synthetic Organic Chemistry†

"United we stand, divided we fall."--Aesop. Aggregation-induced emission (AIE) refers to a photophysical phenomenon shown by a group of luminogenic materials that are non-emissive when they are dissolved in good solvents as molecules but become highly luminescent when they are clustered in poor solvents or solid state as aggregates. In this Review we summarize the recent progresses made in the area of AIE research. We conduct mechanistic analyses of the AIE processes, unify the restriction of intramolecular motions (RIM) as the main cause for the AIE effects, and derive RIM-based molecular engineering strategies for the design of new AIE luminogens (AIEgens). Typical examples of the newly developed AIEgens and their high-tech applications as optoelectronic materials, chemical sensors and biomedical probes are presented and discussed.

Aggregation-Induced Emission: The Whole Is More Brilliant than the Parts

In studying the evolution of organic chemistry and grasping its essence, one comes quickly to the conclusion that no other type of reaction plays as large a role in shaping this domain of science than carbon-carbon bond-forming reactions. The Grignard, Diels-Alder, and Wittig reactions are but three prominent examples of such processes, and are among those which have undeniably exercised decisive roles in the last century in the emergence of chemical synthesis as we know it today. In the last quarter of the 20th century, a new family of carbon-carbon bond-forming reactions based on transition-metal catalysts evolved as powerful tools in synthesis. Among them, the palladium-catalyzed cross-coupling reactions are the most prominent. In this Review, highlights of a number of selected syntheses are discussed. The examples chosen demonstrate the enormous power of these processes in the art of total synthesis and underscore their future potential in chemical synthesis.

Palladium-catalyzed cross-coupling reactions in total synthesis.

Stereocontrolled synthesis of tetrasubstituted olefins.

Aqueous Enantioselective Organocatalytic Diels−Alder Reactions Employing Hydrazide Catalysts. A New Scaffold for Organic Acceleration

A variety of medium-sized thionolactones have been prepared and condensed with nucleophiles giving alkylated thioacetals upon quenching with methyl iodide. Reductive desulfurization using triphenyltin hydride under radical conditions afforded the corresponding cyclic ethers rapidly and efficiently and, in most cases, with complete stereocontrol. This methodology has been proven through the construction of model systems of rings B and D of brevetoxin A (1) and a synthesis of (±)-lauthisan

Synthesis of medium-sized ring ethers from thionolactones. Applications to polyether synthesis

A compound of formula (I), wherein X is CF3, C2F5, 2-benzothiazole, CF2CONHR6, CONHR6, wherein R6 is CH2C6H5, CH2(4-iodophenyl), CH3, (CH2)2OCH2C6H5, CH2-2-benzimidazole, CH2-(3,4-methylenedioxybenzene), CH(CH3)C6H5 or CH(CH2CH3)C6H5; or X is 2-benzoxazole-R7 wherein R7 is H, 4-CH3, 5-CH3, 6-CH3 or 7-CH3; R1 is H, CH3 or CH2CH3; R2 is CH2CONH2, CH2CH2CONH2, CH2-thiazole, CH2CON(CH3)2, CH2CO-(pyrrolidino), CH2CH(CH3)2 or CH2C6H5; R3 is Et, CH(CH3)2, C(CH3)3, adamantyl, CH2C(CH3)3 or C(CH3)2CO2H; and R20 is COCH2C(CH3)3, COCH2CH2C6H4OH, COCH2CH(CH3)2, CO2C(CH3)3, CONHC(CH3)3, COCH2N(CH3)2, CO(CH2)3CO2H, CO-(S)-CH(NH2)C(CH3)3, CO-(S)-CH{NHC(O)O-C(CH3)3}C(CH3)3, CO-(S)-CH{NHCO(CH2)5NHC(O)OC(CH3)3}C(CH3)3 or CO-(S)-CH{NHCO(CH2)5NH2}C(CH3)3. These compounds are useful for the treatment of human cytomegalovirus infection.

Peptidomimetic inhibitors of the human cytomegalovirus protease

A significant redesign of the introductory organic chemistry curriculum at the authors’ institution is described. There are two aspects that differ greatly from a typical functional group approach. First, organic reaction mechanisms and the electron-pushing formalism are taught before students have learned a single reaction. The conservation of electrons, atoms, and formal charges, how the use of curved arrows helps describe the mechanism, and how to predict reaction mechanisms are emphasized. Second, the reactions taught in the first two semesters of organic chemistry are arranged by their governing mechanism, rather than by functional group. The reactions are taught in order of increasing difficulty, beginning with acid–base reactions, followed by simple additions to π electrophiles, and ending the first semester with addition to π nucleophiles, including aromatic chemistry. The reactions in the second organic semester begin with elimination reactions, then substitutions, and finally more complex π nucl...

William W. Ogilvie

Papers

Stereocontrolled synthesis of tetrasubstituted olefins.

Aqueous Enantioselective Organocatalytic Diels−Alder Reactions Employing Hydrazide Catalysts. A New Scaffold for Organic Acceleration

Synthesis of medium-sized ring ethers from thionolactones. Applications to polyether synthesis

Peptidomimetic inhibitors of the human cytomegalovirus protease

Mechanisms before Reactions: A Mechanistic Approach to the Organic Chemistry Curriculum Based on Patterns of Electron Flow