Biocatalysis represents a key pillar in the modern toolbox of the organic chemist for the selective preparation of complex molecules. The natural reaction portfolio, however, is limited and does only cover a smaller subset of transformations that would be useful in the context of organic synthesis. Over the past two decades, researchers have tried to expand the reaction scope of enzymes in order to make these attractive catalysts more generally applicable and to reach even broader acceptance in the chemical community. This chapter highlights different strategies that can provide protein-based catalysts with new-to-nature reactivities. The approaches to teach enzymes the art of synthetic chemistry include directed evolution, de novo design, visible light photoactivation as well as the introduction of abiotic species through cofactor exchange or artificial metal binding sites.
Phosphines are indispensable ligands in homogeneous catalysis and have made crucial contributions to the development of new reactions or the improvement of existing reaction protocols. Electron-rich phosphines have proven beneficial in many transformations. For a long time the donor strength was limited by the electron-donating power of conventional alkyl groups and thus reached a maximum in trialkylphosphines such as PtBu3 and PAd(3). However, in recent years, unconventional substituents with stronger electron-donating abilities have been developed, allowing a further increase in the donor capacity. In this way, phosphines have been developed with a donor strength that is comparable or even superior to that of N-heterocyclic carbenes. This review article summarizes concepts that enabled this impressive increase in the donor capacity of phosphine ligands. While focusing on substituents bearing alpha-carbanionic units, it also compares their properties to those of heteroatom substituents and discusses their application in homogeneous catalysis.
A selection of enantioselective catalysts will be presented, ordered by the symmetry group to which they belong. The symmetry groups will be illustrated with examples from plant and animal kingdom, restricting ourselves to the ones the readers may be familiar with. A few man-made utensils complete the picture.
Life relies on enzymes, which are involved in speeding up all chemical reactions that occur in our body within a biologically compatible timeframe. Enzymes also present beneficial properties such as high specificity and selectivity and the ability to function under very mild biological conditions. These advantageous characteristics have awakened the interest among scientists to create enzymes for industrial purposes. Many different experimental and computational approaches have been developed along the years, but so far none of them is able to design efficient tailor-made enzymes at a reduced economic cost. This chapter describes the high complexity of enzymatic catalysis and provides an overview of the computational strategies that have been developed for capturing the key enzymatic features for enhanced properties. Some examples of recently developed computational pipelines for understanding and designing enhanced enzymatic function from our lab are finally presented.
This chapter focus on recent advances in the design of ruthenium-based nanoparticles using organometallic complexes as the metal source, for their application in catalysis. The aim is to illustrate the advantages of the organometallic approach to achieve nanoparticles with controlled characteristics. The adjustment of the morphology (size, shape, crystalline structure) and of the surface state of metal nanoparticles, are key parameters for the tuning of their catalytic properties. Study and rationalize the effects of these parameters provides interesting perspectives to improve the performance of nanocatalysts. At the laboratory scale, the accurate design of metal nanoparticles is feasible by an adequate choice of the reaction conditions including the nature of the metal precursor (organometallic complex with appropriate kinetics of decomposition), the nature of the stabilizer (polymers, dendrimers, ligands, ionic liquids, etc.), the addition of a second metal for a synergy effect or the use of a support that will bring other properties (stability, conductivity, electronic effects by phosphorus- or nitrogen doping, confinement effect). The challenge is to find the best compromise to achieve robust metal nanoparticles with high catalytic performance, both in terms of activity and selectivity. This will be illustrated through recent examples of ruthenium nanoparticles implemented in catalytic reactions that can find applications in fine chemistry and energy. The complementarity between computational and experimental chemistries, when available, will be underlined, being a powerful way to precisely understand the catalytic properties of nanoparticles and then, improve performance.
Enantioselective synthesis remains an important and challenging area of research in organic synthesis. Among the available methods, the use of multicatalysis-based approaches to develop new enantioselective reactions has gained remarkable attention in the past few decades. This book chapter will cover all such enantioselective reactions that employ gold catalysts in conjunction with (a) metal catalysis, (b) NHC catalysis, (c) phosphine catalysis, (d) Bronsted acid catalysis, and (e) amine catalysis. The mechanisms for all the reactions have been discussed in brief and the appropriate transition states have also been presented.
In recent years, multicatalysis has evolved into an attractive strategy for the synthesis of complex molecules from simple starting materials. Multicatalysis can either facilitate existing synthetic methods by reducing time, waste and cost or enable new transformations that are impossible using classic approaches. This chapter introduces three different categories of multicatalysis (cooperative, domino, and relay catalysis). The classification is based on the number of catalysts used for a transformation and how their respective catalytic cycles interact with one another. The opportunities introduced by each category are discussed and illustrated with selected examples in the context of enantioselective C-C bond formation reactions. Lastly, a brief discussion of "complex systems", i.e., systems of higher complexity beyond the aforementioned classification, is provided.
