C-C Bond Formation via Direct Functionalization of Indolizines with a Bichromophoric Ruthenium Photocatalyst
Kevin Klaus Stefanoni1, René Wilhelm1
1Institute of Organic Chemistry, Clausthal University of Technology, Leibnizstr. 6, Clausthal-Zellerfeld 38678, Germany.
ACS Organic & Inorganic Au
|April 6, 2026
Summary
This study introduces a new photocatalyzed method for synthesizing substituted indolizines using readily available reagents and a novel ruthenium catalyst. This green chemistry approach offers high yields for drug design scaffolds.
Area of Science:
- Organic Chemistry
- Catalysis
- Medicinal Chemistry
Background:
- Indolizine derivatives are important scaffolds in medicinal chemistry.
- Efficient synthesis of 3-alkylated indolizines remains a challenge.
- Photocatalysis offers a sustainable approach to organic synthesis.
Purpose of the Study:
- To develop an unprecedented photocatalyzed radical C–C bond formation protocol.
- To synthesize a range of substituted 3-alkylated indolizine derivatives.
- To explore the utility of the method for other N-heteroarenes.
Main Methods:
- Utilized 2-mercaptothiazolidinium salts as radical sources.
- Employed a novel dyad-like Ruthenium complex as a photoredox catalyst.
- Conducted the reaction under green light irradiation.
Main Results:
- Achieved yields of up to 99% for substituted 3-alkylated indolizines.
- Demonstrated a mild, robust, and chemoselective procedure.
- Successfully alkylated other N-heteroarenes like indoles and indazoles.
Conclusions:
- The developed protocol provides a convenient and efficient synthesis of valuable indolizine derivatives.
- The method is applicable to a broader range of N-heteroarenes.
- The resulting alkylated products serve as significant scaffolds for drug design.
![[DPEPhosbcpCu]PF6: A General and Broadly Applicable Copper-Based Photoredox Catalyst](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F59739.jpg&w=3840&q=50)
Related Concept Videos
01:18Benzene to 1,4-Cyclohexadiene: Birch Reduction Mechanism
2.8K
Birch reduction uses solvated electrons as reducing agents. The reaction converts benzene to 1,4-cyclohexadiene. The reaction proceeds by the transfer of a single electron to the ring to form a benzene radical anion. This anion is highly basic—it abstracts a proton from the alcohol to form a cyclohexadienyl radical. Another single electron transfer gives the cyclohexadienyl anion. A proton transfer from the alcohol forms 1,4-cyclohexadiene. Since this reduction occurs via radical anion...
2.8K
01:26Photochemical Electrocyclic Reactions: Stereochemistry
2.4K
The absorption of UV–visible light by conjugated systems causes the promotion of an electron from the ground state to the excited state. Consequently, photochemical electrocyclic reactions proceed via the excited-state HOMO rather than the ground-state HOMO. Since the ground- and excited-state HOMOs have different symmetries, the stereochemical outcome of electrocyclic reactions depends on the mode of activation; i.e., thermal or photochemical.
Selection Rules: Photochemical Activation
Selection Rules: Photochemical Activation
2.4K
01:27Cyclohexenones via Michael Addition and Aldol Condensation: The Robinson Annulation
3.1K
Robinson annulation is a base-catalyzed reaction for the synthesis of 2-cyclohexenone derivatives from 1,3-dicarbonyl donors (such as cyclic diketones, β-ketoesters, or β-diketones) and α,β-unsaturated carbonyl acceptors. Named after Sir Robert Robinson, who discovered it, this reaction yields a six-membered ring with three new C–C bonds (two σ bonds and one π bond).
3.1K
02:24Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation
9.6K
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.
9.6K
01:11ortho–para-Directing Activators: –CH3, –OH, –NH2, –OCH3
8.0K
All ortho–para directors, excluding halogens, are activating groups. These groups donate electrons to the ring, making the ring carbons electron-rich. Consequently, the reactivity of the aromatic ring towards electrophilic substitution increases. For instance, the nitration of anisole is about 10,000 times faster than the nitration of benzene. The electron-donating effect of the methoxy group in anisole activates the ortho and para positions on the ring and stabilizes the corresponding...
8.0K
01:29Diels–Alder Reaction Forming Bridged Bicyclic Products: Stereochemistry
6.6K
Diels–Alder reactions between cyclic dienes locked in an s-cis configuration and dienophiles yield bridged bicyclic products.
6.6K