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Lecture

Catalytic Asymmetric Reactions in Organic Chemistry

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 the topic of catalytic asymmetric reactions in organic chemistry, focusing on the LUMO activation of extended pi-systems of carbonyls and imines, asymmetric conjugate addition using a radical-based approach, and the novel use of photoredox catalysis to generate radicals. The instructor discusses the advantages of radical-based mechanisms, the role of light activation, and the catalytic cycles involved in these reactions. Various approaches such as carbene-based and carbenoid-based methods are also explored, along with examples of asymmetric Diels-Alder reactions and their stereochemistry.

Instructor

Jérôme Waser

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

Official source

Related concepts (28)

Carbene

In organic chemistry, a carbene is a molecule containing a neutral carbon atom with a valence of two and two unshared valence electrons. The general formula is or where the R represents substituents or hydrogen atoms. The term "carbene" may also refer to the specific compound , also called methylene, the parent hydride from which all other carbene compounds are formally derived. Carbenes are classified as either singlets or triplets, depending upon their electronic structure.

Asymmetric hydrogenation

Asymmetric hydrogenation is a chemical reaction that adds two atoms of hydrogen to a target (substrate) molecule with three-dimensional spatial selectivity. Critically, this selectivity does not come from the target molecule itself, but from other reagents or catalysts present in the reaction. This allows spatial information (what chemists refer to as chirality) to transfer from one molecule to the target, forming the product as a single enantiomer.

Catalysis

Catalysis (kəˈtæləsɪs) is the process of change in rate of a chemical reaction by adding a substance known as a catalyst (ˈkætəlɪst). Catalysts are not consumed by the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recycles quickly, very small amounts of catalyst often suffice; mixing, surface area, and temperature are important factors in reaction rate. Catalysts generally react with one or more reactants to form intermediates that subsequently give the final reaction product, in the process of regenerating the catalyst.

Radical (chemistry)

In chemistry, a radical, also known as a free radical, is an atom, molecule, or ion that has at least one unpaired valence electron. With some exceptions, these unpaired electrons make radicals highly chemically reactive. Many radicals spontaneously dimerize. Most organic radicals have short lifetimes. A notable example of a radical is the hydroxyl radical (HO·), a molecule that has one unpaired electron on the oxygen atom. Two other examples are triplet oxygen and triplet carbene (꞉CH2) which have two unpaired electrons.

Persistent carbene

A persistent carbene (also known as stable carbene) is a type of carbene demonstrating particular stability. The best-known examples and by far largest subgroup are the N-heterocyclic carbenes (NHC) (sometimes called Arduengo carbenes), for example diaminocarbenes with the general formula (R2N)2C:, where the four R moieties are typically alkyl and aryl groups. The groups can be linked to give heterocyclic carbenes, such as those derived from imidazole, imidazoline, thiazole or triazole.

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Catalytic Asymmetric Reactions in Organic Chemistry

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Catalytic Asymmetric Reactions in Organic Synthesis

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Catalytic Asymmetric Reactions in Organic Chemistry

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Related concepts (28)

Carbene

Asymmetric hydrogenation

Catalysis

Radical (chemistry)

Persistent carbene