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

Dioxygen activation at mononuclear nonheme iron active sites: enzymes, models, and intermediates.

Green solvents for sustainable organic synthesis: state of the art

Based on the principles and metrics of green chemistry and sustainable development, biocatalysis is both a green and sustainable technology. This is largely a result of the spectacular advances in molecular biology and biotechnology achieved in the past two decades. Protein engineering has enabled the optimization of existing enzymes and the invention of entirely new biocatalytic reactions that were previously unknown in Nature. It is now eminently feasible to develop enzymatic transformations to fit predefined parameters, resulting in processes that are truly sustainable by design. This approach has successfully been applied, for example, in the industrial synthesis of active pharmaceutical ingredients. In addition to the use of protein engineering, other aspects of biocatalysis engineering, such as substrate, medium, and reactor engineering, can be utilized to improve the efficiency and cost-effectiveness and, hence, the sustainability of biocatalytic reactions. Furthermore, immobilization of an enzyme ...

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Role of Biocatalysis in Sustainable Chemistry

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Studies in Surface Science and Catalysis

Herein we review recent advances in the asymmetric reduction of ketones by biocatalysts. Included are discussions on recent developments in methodologies to control enantioselectivities of catalytic reactions, and examples of practical applications that reduce various types of ketones are also shown.

Recent developments in asymmetric reduction of ketones with biocatalysts

Latest advances for asymmetric synthesis through reduction and oxidation including deracemization by biocatalysts are reviewed. Newly developed methodologies as well as practical applications are covered.

Recent progress in biocatalysis for asymmetric oxidation and reduction

Stereochemical control of microbial reduction. 17. A method for controlling the enantioselectivity of reductions with bakers' yeast

L'oxoetanoate ethyl-2 est reduit par 3 methodes: la levure Saccharomyces cerevisiae libre en milieu aqueux, la levure immobilisee dans l'eau, la levure immobilisee dans l'hexane. La stereochimie de la reduction des alpha ceto esters par Saccharomyces cerevisiae est controlee par des conditions de reaction specifiques

Kaoru Nakamura

Papers

Recent developments in asymmetric reduction of ketones with biocatalysts

Recent progress in biocatalysis for asymmetric oxidation and reduction

Stereochemical control of microbial reduction. 17. A method for controlling the enantioselectivity of reductions with bakers' yeast

Stereochemical control on yeast reduction of .alpha.-keto esters. Reduction by immobilized bakers' yeast in hexane

Asymmetric reduction of ketones by the acetone powder of geotrichum candidum