Enzymatic and homogeneous catalysis offer complementary means to produce enantiopure products. Incorporation of achiral, biotinylated aminodiphosphine-rhodium complexes in (strept)avidin affords enantioselective hydrogenation catalysts. A combined chemogenetic procedure allows the optimization of the activity and the selectivity of such artificial metalloenzymes: the reduction of acetamidoacrylate proceeds to produce N-acetamidoalanine in either 96 % ee (R) or 80 % ee (S). In addition to providing a chiral second coordination sphere and, thus, selectivity to the catalyst, the phenomenon of protein-accelerated catalysis (e.g., increased activity) was unraveled. Such artificial metalloenzymes based on the biotin-avidin technology display features that are reminiscent of both homogeneous and of enzymatic catalysis.

In the past few years, supramolecular chemistry has led to new approaches in homogeneous catalysis. While host-guest chemistry had already found applications in catalysis as a result of the pioneering work carried out by Professor Ronald Breslow and Nobel prizewinner Professor Jean-Marie Lehn that began some 40 years ago, the construction of catalysts by supramolecular forces has only recently become a powerful tool. This development paves the way for large numbers of new potential catalysts that can be varied in an expedient way by changing the constituting building blocks. Written by some of the leading contributors in the field, this book is intended for both industrial and academic chemists with an interest in this area of catalysis. With its discussion of topics from ligand libraries to chirality-directed self-assembly, this is a must-have for chemists with organic, catalytic and polymer backgrounds, as well as those employing such compounds in industrial processes.

The inclusion of small guest molecules within suitable host compounds results in constrained systems that imbue novel properties upon the incarcerated organic substrates. Supramolecular tactics are becoming widely employed and this treatise spotlights them. Often, the impact of encapsulation on product formation is substantial. The use of constrained systems offers the means to steer reactions along desired pathways. A broad overview of various supramolecular approaches aimed to manipulate chemical reactions are featured. The following topics are covered in detail: - general concepts governing the assembly of the substrate with the reaction vessel - preparation of molecular reactors - stabilization of reactive intermediates - reactions in water, in organic solvents, and in the solid state - photochemical reactions - reactions with unusual regioselectivity Molecular Encapsulation: Organic Reactions in Constrained Systems is an essential guide to the art of changing the outcome and the selectivity of a chemical reaction using nano-sized reaction vessels. It will find a place on the bookshelves of students and researchers working in the areas of supramolecular chemistry, nanotechnology, organic and pharmaceutical chemistry, and materials science as well.

Enantioselective catalysis is one of the most efficient ways to synthesize high-added-value enantiomerically pure organic compounds. As the subtle details which govern enantioselection cannot be reliably predicted or computed, catalysis relies more and more on a combinatorial approach. Biocatalysis offers an attractive, and often complementary, alternative for the synthesis of enantiopure products. From a combinatorial perspective, the potential of directed evolution techniques in optimizing an enzyme's selectivity is unrivaled. In this review, attention is focused on the construction of artificial metalloenzymes for enantioselective catalytic applications. Such systems are shown to combine properties of both homogeneous and enzymatic kingdoms. This review also includes our recent research results and implications in the development of new semisynthetic metalloproteins for the enantioselective hydrogenation of N-protected dehydro-amino acids.

Reactions catalyzed by metalloenzymes have great potential for applications in the biotechnology and pharmaceutical industries. While only a few of these enzymes have yet been used in such applications, in the last few decades numerous efficient, selective, environmentally friendly and economical synthetic analogues have been described, including supramolecular, polymeric, nanoparticulate and lowmolecular- weight organometallic complexes, and metal organic frameworks. In this Research Topic, we present a collection of original research and review articles that show significant recent advances made in the rational design of such artificial metalloenzymes.

Giovanni Poli, Guillaume Prestat, Frédéric Liron, Claire Kammerer-Pentier: Selectivity in Palladium Catalyzed Allylic Substitution.- Jonatan Kleimark and Per-Ola Norrby: Computational Insights into Palladium-mediated Allylic Substitution Reactions.- Ludovic Milhau, Patrick J. Guiry: Palladium-catalyzed enantioselective allylic substitution.- Wen-Bo Liu, Ji-Bao Xia, Shu-Li You: Iridium-Catalyzed Asymmetric Allylic Substitutions.- Christina Moberg: Molybdenum- and Tungsten-Catalyzed Enantioselective Allylic Substitutions.- Jean-Baptiste Langlois, Alexandre Alexakis: Copper-catalyzed enantioselective allylic substitution.- Jeanne-Marie Begouin, Johannes E. M. N. Klein, Daniel Weickmann, B. Plietker: Allylic Substitutions Catalyzed by Miscellaneous Metals.- Barry M. Trost, Matthew L. Crawley: Enantioselective Allylic Substitutions in Natural Product Synthesis.