Related Experiment Video
Updated: May 22, 2026

Palladium N-Heterocyclic Carbene Complexes: Synthesis from Benzimidazolium Salts and Catalytic Activity in Carbon-carbon Bond-forming Reactions
Published on: July 30, 2017
N-Aryl Acridone Derivatives as Effective Catalysts for Energy Transfer Reactions
Francesco Calogero1,2, Gaetano D'Onghia1, Federica Fina1,2
1Department of Chemistry "G. Ciamician", ALMA MATER STUDIORUM - Università di Bologna, Bologna, Italy.
None:
Organic photocatalysts capable of promoting high-energy triplet energy transfer (EnT) remain limited, particularly for demanding [2+2] photocycloaddition reactions. In this study, we report the use of readily accessible N-aryl acridones as efficient visible-light-driven organic photocatalysts for challenging EnT processes. Although largely unexplored in photocatalysis, acridone derivatives exhibit photophysical properties suitable for sensitizing substrates with high triplet energies. Using N-Boc-indole-2-methyl ester and coumarin as representative high-triplet-energy substrates, we demonstrate that N-aryl acridones effectively mediate [2+2] cycloadditions under mild conditions via an energy-transfer mechanism. The modular acridone scaffold enables straightforward structural modification through N-functionalization, allowing systematic tuning of electronic and steric parameters to optimize catalytic performance.
Related Concept Videos
Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation
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.
Electrophilic Aromatic Substitution: Friedel–Crafts Acylation of Benzene
ortho–para-Directing Activators: –CH3, –OH, –⁠NH2, –OCH3
Preparation of Alkynes: Alkylation Reaction
Alkylation of terminal alkynes with primary alkyl halides in the presence of a strong base like sodium amide is one of the common methods for the synthesis of longer carbon-chain alkynes. For example, treatment of 1-propyne with sodium amide followed by reaction with ethyl bromide yields 2-pentyne.
Nucleophilic Aromatic Substitution of Aryldiazonium Salts: Aromatic SN1
In the Sandmeyer reaction, for example, the diazonio group is replaced by a chloro, bromo, or cyano...
Amines to Amides: Acylation of Amines
Next, the second equivalent of amine serves as a Brønsted base and deprotonates the quaternary amide...

