Lecture

Lewis and Brønsted acids activation

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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 activation of extended π-systems of carbonyls and imines using Lewis and Brønsted acids, focusing on the conjugate addition and cycloaddition reactions. The instructor presents pioneering examples of conjugate Michael additions by List, Corey, and Meggers, highlighting the challenges and solutions for achieving high enantioselectivity. The lecture also discusses recent/classical examples of conjugate Michael additions using radical nucleophiles and trisoxazoline ligands. Furthermore, it explores the Diels-Alder cycloaddition reactions, including Corey's boranes and their applications in asymmetric synthesis. The lecture concludes with insights into catalytic asymmetric reactions in organic chemistry, emphasizing the development of chiral cobalt catalysts for visible-light-induced radical conjugate addition.

Instructor

Jérôme Waser

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

Official source

Ontological neighbourhood

Chemistry

Inorganic chemistry: Topics in inorganic chemistry

Related concepts (32)

Lewis acids and bases

A Lewis acid (named for the American physical chemist Gilbert N. Lewis) is a chemical species that contains an empty orbital which is capable of accepting an electron pair from a Lewis base to form a Lewis adduct. A Lewis base, then, is any species that has a filled orbital containing an electron pair which is not involved in bonding but may form a dative bond with a Lewis acid to form a Lewis adduct. For example, NH3 is a Lewis base, because it can donate its lone pair of electrons.

Acid

An acid is a molecule or ion capable of either donating a proton (i.e. hydrogen ion, H+), known as a Brønsted–Lowry acid, or forming a covalent bond with an electron pair, known as a Lewis acid. The first category of acids are the proton donors, or Brønsted–Lowry acids. In the special case of aqueous solutions, proton donors form the hydronium ion H3O+ and are known as Arrhenius acids. Brønsted and Lowry generalized the Arrhenius theory to include non-aqueous solvents.

Brønsted–Lowry acid–base theory

The Brønsted–Lowry theory (also called proton theory of acids and bases) is an acid–base reaction theory which was first developed by Johannes Nicolaus Brønsted and Thomas Martin Lowry independently in 1923. The basic concept of this theory is that when an acid and a base react with each other, the acid forms its conjugate base, and the base forms its conjugate acid by exchange of a proton (the hydrogen cation, or H+). This theory generalises the Arrhenius theory.

Acid–base reaction

An acid–base reaction is a chemical reaction that occurs between an acid and a base. It can be used to determine pH via titration. Several theoretical frameworks provide alternative conceptions of the reaction mechanisms and their application in solving related problems; these are called the acid–base theories, for example, Brønsted–Lowry acid–base theory. Their importance becomes apparent in analyzing acid–base reactions for gaseous or liquid species, or when acid or base character may be somewhat less apparent.

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.

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Acids and Bases: Definitions and Equilibrium

Explains acid-base definitions, equilibrium constants, pH scale, conjugate pairs, and buffers.

Catalytic Asymmetric Reactions in Organic Chemistry

Explores catalytic asymmetric reactions in organic chemistry, covering Lewis and Brønsted acids activation, Aldol Reaction, Allylation, Ene Reactions, and more.

Chemical Equilibria and Reactivity

Explores chemical equilibria, weak acids, buffers, titration curves, and indicators in acid-base reactions.

Catalytic Asymmetric Reactions

Covers various catalytic asymmetric reactions in organic chemistry, including Lewis and Brønsted acids activation, Jacobsen Urea Catalyst, and Mannick Reaction.

Acids and Bases: Equilibria and Reactions