Electrophotocatalysis Enables Birch-Type Dearomative Alkylation

Area of Science:

• Organic Chemistry
• Photocatalysis
• Synthetic Methodology

Background:

• Birch-type dearomative alkylation is key for creating sp3-hybridized carbon centers in (hetero)arenes.
• Traditional methods face challenges like competitive protonation and poor alkylation control, yielding undesired 1,4-cyclohexadienes.

Purpose of the Study:

• To develop the first electrophotocatalytic method for Birch-type dearomative alkylation of (hetero)arenes.
• To enable efficient and selective alkylation of aromatic systems under mild conditions.

Main Methods:

• Utilized N,N-bis(2,6-diisopropylphenyl)perylene-3,4,9,10-bis(dicarboximide) as a metal-free electrophotocatalyst.
• Employed alkyl chlorides as alkylating agents in a tandem reaction.
• Investigated reaction mechanisms using control experiments, spectroscopic studies, and DFT calculations.

Main Results:

• Successfully achieved dearomative alkylation of anthracene, naphthalene, and acridine derivatives.
• Identified two reaction pathways: "Birch-SN2" and "XAT-SRN1" for arene radical anions reacting with alkyl chlorides.
• Demonstrated high site selectivity and broad functional group tolerance.

Conclusions:

• The developed electrophotocatalytic method provides a powerful new tool for the direct modification of (hetero)arenes.
• The reaction proceeds under extremely mild conditions, utilizing simulated sunlight and solar electricity.
• This approach shows significant potential for synthesizing complex aromatic frameworks.