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Lecture

Electrophilic Activation of Double Bonds

In course

CH-435: Asymmetric catalysis for fine chemicals synthesis

The asymmetric synthesis of fine chemicals is a research topic of growing importance for the synthesis of modern materials, drugs and agrochemicals. In this lecture, the concepts of asymmetric catalysis for fine chemical synthesis are introduced. ...

Description

This lecture covers various electrophilic activation reactions, including epoxidation, aziridination, cyclopropanation, dihydroxylation, C-H/X-H functionalization, and other reactions. Mechanisms, catalysts, and enantioselectivity in Sharpless dihydroxylation are discussed. The importance of ligand structure in selectivity, asymmetric allylation with different metals, and propargylic substitution reactions are also explored.

Instructor

Jérôme Waser

Jérôme Waser biography and CV's are available on the following website: http://lcso.epfl.ch/waser

Official source

Related concepts (32)

Ligand

In coordination chemistry, a ligand is an ion or molecule with a functional group that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's electron pairs, often through Lewis bases. The nature of metal–ligand bonding can range from covalent to ionic. Furthermore, the metal–ligand bond order can range from one to three. Ligands are viewed as Lewis bases, although rare cases are known to involve Lewis acidic "ligands".

Enantioselective synthesis

Enantioselective synthesis, also called asymmetric synthesis, is a form of chemical synthesis. It is defined by IUPAC as "a chemical reaction (or reaction sequence) in which one or more new elements of chirality are formed in a substrate molecule and which produces the stereoisomeric (enantiomeric or diastereomeric) products in unequal amounts." Put more simply: it is the synthesis of a compound by a method that favors the formation of a specific enantiomer or diastereomer.

Ligand field theory

Ligand field theory (LFT) describes the bonding, orbital arrangement, and other characteristics of coordination complexes. It represents an application of molecular orbital theory to transition metal complexes. A transition metal ion has nine valence atomic orbitals - consisting of five nd, one (n+1)s, and three (n+1)p orbitals. These orbitals are of appropriate energy to form bonding interaction with ligands. The LFT analysis is highly dependent on the geometry of the complex, but most explanations begin by describing octahedral complexes, where six ligands coordinate to the metal.

Asymmetric induction

Asymmetric induction (also enantioinduction) describes the preferential formation in a chemical reaction of one enantiomer or diastereoisomer over the other as a result of the influence of a chiral feature present in the substrate, reagent, catalyst or environment. Asymmetric induction is a key element in asymmetric synthesis. Asymmetric induction was introduced by Hermann Emil Fischer based on his work on carbohydrates. Several types of induction exist.

Osmium tetroxide

Osmium tetroxide (also osmium(VIII) oxide) is the chemical compound with the formula OsO4. The compound is noteworthy for its many uses, despite its toxicity and the rarity of osmium. It also has a number of unusual properties, one being that the solid is volatile. The compound is colourless, but most samples appear yellow. This is most likely due to the presence of the impurity OsO2, which is yellow-brown in colour. In biology, its property of binding to lipids has made it a widely-used stain in electron microscopy.

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Catalytic Asymmetric Reactions in Organic Chemistry

Covers catalytic asymmetric reactions in organic chemistry, focusing on various methods and mechanisms.

Catalytic Radical Processes: Asymmetric Synthesis of Cyclobutanones

Covers a novel catalytic radical process for asymmetric synthesis of cyclobutanones.

Catalytic Asymmetric Reactions

Explores catalytic asymmetric reactions, including allylic activation, dihydroxylation, aminohydroxylation, and C-H functionalization, emphasizing enantioselectivity and regioselectivity.