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Related Concept Videos

Radical Reactivity: Overview01:11

Radical Reactivity: Overview

2.1K
Radicals, the highly reactive species, gain stability by undergoing three different reactions. The first reaction involves a radical-radical coupling, in which a radical combines with another radical, forming a spin‐paired molecule. The second reaction is between a radical and a spin‐paired molecule, generating a new radical and a new spin‐paired molecule. The third reaction is radical decomposition in a unimolecular reaction, forming a new radical and a spin‐paired...
2.1K
Radical Formation: Addition00:47

Radical Formation: Addition

1.7K
Radicals can be formed by adding a radical to a spin-paired molecule. This is typically observed with unsaturated species, where the addition of a radical across the π bond leads to the production of a new radical by dissolving the π bond. For example, the addition of a Br radical to an alkene yields a carbon-centered radical.
Similar to charge conservation in chemical reactions, spin conservation is implicit for radical reactions. Accordingly, the product formed must possess an...
1.7K
Radical Formation: Overview01:03

Radical Formation: Overview

2.1K
A bond can be broken either by heterolytic bond cleavage to form ions or homolytic bond cleavage to yield radicals. A fishhook arrow is used to represent the motion of a single electron in homolytic bond cleavage. There are two main sources from which radicals can be formed:
Radicals from spin-paired molecules:
Radicals can be obtained from spin-paired molecules either by homolysis or electron transfer. While two radicals are formed in the former, an electron is added in the...
2.1K
Radical Autoxidation01:20

Radical Autoxidation

2.2K
The oxidation of an organic compound in the presence of air or oxygen is called autoxidation. For example, cumene reacts with oxygen to form hydroperoxide. Autoxidation involves initiation, propagation, and termination steps. Many organic compounds are susceptible to autoxidation—especially ethers in the presence of oxygen, which form hydroperoxides. Even though this reaction is slow, old ether bottles contain small amounts of peroxide, which leads to laboratory explosions during ether...
2.2K
Vicinal Diols via Reductive Coupling of Aldehydes or Ketones: Pinacol Coupling Overview01:27

Vicinal Diols via Reductive Coupling of Aldehydes or Ketones: Pinacol Coupling Overview

1.8K
Wilhelm Rudolph Fittig discovered the pinacol coupling reaction in 1859. It is a radical dimerization reaction and involves the reductive coupling of aldehydes or ketones in the presence of hydrocarbon solvent to yield vicinal diols.
1.8K
Radical Formation: Elimination00:51

Radical Formation: Elimination

1.8K
Another method of radical formation is the elimination process. It is the opposite of the addition route and is driven by the instability of the radical. For example, as depicted in Figure 1, dibenzoyl peroxide yields a pair of unstable radicals upon homolysis. Given its instability, this radical spontaneously undergoes elimination via a C–C bond cleavage to form a relatively more stable phenyl radical. The mechanism involves cleavage of the bond between the α and β positions...
1.8K

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Related Experiment Video

Updated: Aug 5, 2025

Atom Transfer Radical Polymerization of Functionalized Vinyl Monomers Using Perylene as a Visible Light Photocatalyst
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Atom Transfer Radical Polymerization of Functionalized Vinyl Monomers Using Perylene as a Visible Light Photocatalyst

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Photoenzymes for Radical C-C Coupling.

Rui Guo1, Heyu Chen1, Yang Yang1,2

  • 1Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, CA 93106, USA.

Nature Catalysis
|March 27, 2023
PubMed
Summary
This summary is machine-generated.

Researchers repurposed nicotinamide adenine dinucleotide (phosphate) (NAD(P)H)-dependent ketoreductases (KREDs) as photoenzymes. These engineered enzymes efficiently catalyze asymmetric radical carbon-carbon couplings, a significant advance in synthetic chemistry.

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Area of Science:

  • Synthetic organic chemistry
  • Biocatalysis
  • Photoredox catalysis

Background:

  • Asymmetric radical reactions are crucial for synthesizing complex molecules.
  • Developing general catalytic methods for these transformations remains a challenge.
  • Nicotinamide adenine dinucleotide (phosphate) (NAD(P)H)-dependent ketoreductases (KREDs) are enzymes typically involved in ketone reductions.

Purpose of the Study:

  • To engineer KREDs as photoenzymes for asymmetric radical C-C couplings.
  • To overcome limitations of existing catalytic methods for radical reactions.
  • To expand the scope of biocatalysis in asymmetric synthesis.

Main Methods:

  • Engineering of NAD(P)H-dependent ketoreductases (KREDs) to function as photoenzymes.
  • Utilizing engineered KREDs to catalyze asymmetric radical carbon-carbon bond formation.
  • Employing photochemical activation for the catalytic process.

Main Results:

  • Successfully repurposed KREDs as highly efficient photoenzymes.
  • Demonstrated the capability of engineered KREDs to catalyze asymmetric radical C-C couplings.
  • Achieved high efficiency and selectivity in the radical coupling reactions.

Conclusions:

  • Engineered KREDs represent a novel and efficient class of photoenzymes.
  • This approach provides a new general catalytic strategy for asymmetric radical transformations.
  • Biocatalysis offers a powerful platform for advancing asymmetric radical chemistry.