Related Experiment Video
Updated: Jul 12, 2025
06:46
Facile Preparation of 2Z,4E-Dienamides by the Olefination of Electron-deficient Alkenes with Allyl Acetate
Published on: June 21, 2017
7.5K
Radical Termination via β-Scission Enables Photoenzymatic Allylic Alkylation Using "Ene"-Reductases
Netgie Laguerre1,2, Paul S Riehl1,2, Daniel G Oblinsky1,2
1Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States.
ACS Catalysis
|October 20, 2023
Summary
Researchers developed a novel photoenzymatic allylation using engineered flavin-dependent
Area of Science:
- Organic Chemistry
- Biocatalysis
- Photochemistry
Background:
- Allylation reactions are crucial for C-C bond formation and introducing alkene functionalities.
- Flavin-dependent 'ene'-reductases (EREDs) are enzymes with potential for catalyzing radical reactions.
- Traditional radical allylations often involve different termination pathways.
Purpose of the Study:
- To develop a photoenzymatic allylation method using EREDs and allyl silanes.
- To explore the catalytic capabilities of engineered EREDs in annulative allylic alkylation.
- To investigate novel radical termination mechanisms mediated by EREDs.
Main Methods:
- Utilized engineered flavin-dependent 'ene'-reductases (EREDs) for photoenzymatic allylation.
- Employed allyl silanes as substrates for the allylation of α-chloroamides.
- Applied ultrafast transient absorption spectroscopy to elucidate the reaction mechanism.
Main Results:
- Successfully catalyzed the annulative allylic alkylation to synthesize 5, 6, and 7-membered lactams with high enantioselectivity.
- Discovered a novel radical termination mechanism involving β-scission of the silyl group, generating a silyl radical.
- Demonstrated the applicability of this method to intermolecular couplings with allyl sulfones and silyl enol ethers.
Conclusions:
- Engineered EREDs can mediate photoenzymatic allylation with a unique radical termination pathway.
- This work expands the scope of EREDs in catalyzing radical transformations beyond hydrogen atom transfer.
- The developed method offers a versatile strategy for synthesizing complex lactam structures.
Related Concept Videos
02:17Reduction of Alkenes: Asymmetric Catalytic Hydrogenation
3.3K
Catalytic hydrogenation of alkenes is a transition-metal catalyzed reduction of the double bond using molecular hydrogen to give alkanes. The mode of hydrogen addition follows syn stereochemistry.
The metal catalyst used can be either heterogeneous or homogeneous. When hydrogenation of an alkene generates a chiral center, a pair of enantiomeric products is expected to form. However, an enantiomeric excess of one of the products can be facilitated using an enantioselective reaction or an...
The metal catalyst used can be either heterogeneous or homogeneous. When hydrogenation of an alkene generates a chiral center, a pair of enantiomeric products is expected to form. However, an enantiomeric excess of one of the products can be facilitated using an enantioselective reaction or an...
3.3K
02:24Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation
7.8K
Introduction
Like alkenes, alkynes can be reduced to alkanes in the presence of transition metal catalysts such as Pt, Pd, or Ni. The reaction involves two sequential syn additions of hydrogen via a cis-alkene intermediate.
Like alkenes, alkynes can be reduced to alkanes in the presence of transition metal catalysts such as Pt, Pd, or Ni. The reaction involves two sequential syn additions of hydrogen via a cis-alkene intermediate.
7.8K
01:16Radical Reactivity: Nucleophilic Radicals
2.1K
Radicals adjacent to electron-donating groups are called nucleophilic radicals. These radicals readily react with electrophilic alkenes. The SOMO–LUMO interactions are the driving force for the reaction, where the high-energy SOMO of the electron-rich, nucleophilic radicals interacts with the low-energy LUMO of the electron-deficient, electrophilic alkenes. Such SOMO–LUMO interactions are the basis of reactive radical traps, affecting the selectivity in radical reactions. For...
2.1K
01:10α-Alkylation of Ketones via Enolate Ions
3.1K
Ketones with α protons are deprotonated by strong bases like lithium diisopropylamide (LDA) to form enolate ions. The anion is stabilized by resonance, and its hybrid structure exhibits negative charges on the carbonyl oxygen and the α carbon. This ambident nucleophile can attack an electrophile via two possible sites: the carbonyl oxygen, known as O-attack, or the α carbon, known as C-attack. The nucleophilic attack via the carbanionic site is preferred. This is due to the...
3.1K
01:17Radical Anti-Markovnikov Addition to Alkenes: Mechanism
3.8K
The reaction of hydrogen bromide with alkenes in the presence of hydroperoxides or peroxides proceeds via anti-Markovnikov addition. The radical chain reaction comprises initiation, propagation, and termination steps.
The mechanism starts with chain initiation, which involves two steps. In the first chain initiation step, a weak peroxide bond is homolytically cleaved upon mild heating to form two alkoxy radicals. In the second initiation step, a hydrogen atom is abstracted by the alkoxy...
The mechanism starts with chain initiation, which involves two steps. In the first chain initiation step, a weak peroxide bond is homolytically cleaved upon mild heating to form two alkoxy radicals. In the second initiation step, a hydrogen atom is abstracted by the alkoxy...
3.8K
01:27Radical Substitution: Allylic Bromination
5.1K
In organic synthesis, the formation of products can be altered by changing the reaction conditions. For example, a dibromo addition product is formed when propene is treated with bromine at room temperature. In contrast, propene undergoes allylic substitution in non-polar solvents at high temperatures to give 3-bromopropene. In order to avoid the addition reaction, the bromine concentration must be kept as low as possible throughout the reaction. This can be achieved using N-bromosuccinimide...
5.1K