Abstract The chapter describes synthetically useful strategies for α-oxygenation of carbonyl compounds, with special emphasis on recent methods for catalytic and asymmetric reactions. The oxidation of enolates, enols, enol ethers, and α,β-unsaturated compounds is discussed in detail. Classical oxidation reagents like metal oxides, molecular oxygen, peroxides, and peracids are covered, with asymmetric dihydroxylation of enol ethers giving the highest enantioselectivities together with organocatalytic methods using peroxides. Oxaziridines, nitrosoarenes, and hypervalent iodine compounds are more recently developed α-oxygenation alternatives that allow metal-free oxidations under mild conditions. The combination of nitrosoarenes with organocatalysis is currently the best method for enantioselective α-oxygenations. The area of asymmetric α-oxygenations with hypervalent iodine compounds is currently under development, and high enantioselectivities have only been achieved in intramolecular reactions and epoxidations.

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NMR spectroscopy techniques in conjunction with molecular dynamics simulations facilitate description of conformation and dynamics of oligosaccharides in solution. Herein we describe approaches based on hetero-nuclear carbon-proton spin-spin coupling constants useful for assessing conformational preferences at the glycosidic linkage, exemplified for á-cyclodextrin. Furthermore, we utilize hetero-nuclear carbon-proton residual dipolar couplings together with molecular dynamics simulations in the analysis of the conformational dynamics of the milk oligosaccharide Lacto-N-neotetraose.

This chapter focuses on recent developments in metal-free and metal-catalyzed arylations with diaryliodonium salts (diaryl-λ3-iodanes). Synthetic routes to diaryliodonium salts are briefly described, and chemoselectivity trends with unsymmetric iodonium salts are discussed.

Vinylepoxides have become important intermediates in organic synthesis. The main reason for this is the development of selective methods for their subsequent transformations. As vinylepoxides are a special type of allylic electrophiles, it is necessary to control both the regioselectivity and the diastereoselectivity in their reactions with nucleophiles. The practical usefulness of vinylepoxides in synthesis will, however, always be dictated by their availability. Several methods for the asymmetric preparation of vinyloxiranes have been developed and it can be expected that the use of these compounds in organic synthesis will increase. This chapter starts with a discussion of the available techniques for preparing vinylepoxides, with emphasis on asymmetric methods. In the second part various transformations of vinylepoxides are summarized.

Glycans are often linked to proteins or lipids in the form of glycoconjugates but these highly complex molecules also have biological functions as oligosaccharides per se. The limited dispersion in NMR spectra of carbohydrates makes their analysis and interpretation very cumbersome. The computer program CASPER, which is a web-based tool, facilitates prediction ¹H and ¹³C NMR chemical shifts of oligo- or polysaccharide structures defined by the user, makes it possible to carry out an NMR-based sugar analysis including determination of absolute configuration and to perform structure elucidation of unknown glycans using unassigned NMR spectra as input to the program. The output from the program contains, inter alia, tentatively assigned NMR resonances, proposed sugar components, structural suggestions ranked according to the similarity between their predicted chemical shifts and the experimental data as well as 3D structures in pdb-format generated seamlessly by the CarbBuilder program as a part of the CASPER-GUI.

Application of pincer complexes in catalytic applications is a rapidly expanding field in organic synthesis. This chapter is mainly focused on selective formation of carbon carbon, carbon nitrogen, and carbon metal (C B, C Si, and S-Sn) bonds, as well as transfer hydrogenation reactions. The described pincer-complex catalyzed processes are more efficient and more selective than the corresponding transformations catalyzed by metal salts and added ligands. Some of the described pincer-complex catalyzed reactions are not amenable by traditional metal catalysts at all. It has been demonstrated that the superiority of pincer-complex catalysts over the traditional ones is based on the high stability and well-defined structure and stoichiometry of these species. These properties of pincer complexes allow a rational design of active and highly selective catalysts.