DiazaChrysenes (DC): Nitrogen-Containing π-Extended Molecules for Photocatalytic C-H Amination

Area of Science:

• Organic Chemistry
• Photocatalysis
• Heterocyclic Chemistry

Background:

• Metal-free photocatalysis is crucial for sustainable organic synthesis.
• Developing novel organic photocatalysts with tunable properties remains a challenge.

Purpose of the Study:

• To synthesize and characterize a new class of nitrogen-containing π-extended heterocycles, DiazaChrysenes (DCs).
• To evaluate the efficacy of DCs as metal-free photocatalysts for C-H amination.
• To investigate the structure-activity relationship of DCs and their dimeric analogues (dDCs).

Main Methods:

• Synthesis of DC and dDC scaffolds via electrophilic amide activation and arylation.
• Photophysical and redox property characterization.
• Visible-light driven C-H amination reactions with arenes and azoles.
• Computational studies (NCI, ACID, NICS) to elucidate electronic properties.

Main Results:

• Successfully synthesized DC and dDC compounds with tunable photophysical and redox properties.
• CF3-substituted DCs demonstrated high efficiency (up to 85% yield) in metal-free C-H amination of arenes with azoles under visible light and aerobic conditions.
• The reaction showed broad substrate scope and tolerated various arene and azole derivatives.
• dDCs exhibited lower activity compared to DCs, attributed to π-curvature.
• Computational analyses revealed specific electronic characteristics of the DC scaffolds.

Conclusions:

• DiazaChrysenes (DCs) represent a promising new class of synthetically accessible, redox-tunable, metal-free organic photocatalysts.
• DCs enable efficient and sustainable C-H amination reactions under mild conditions.
• The study provides insights into the electronic structure and photocatalytic mechanism of DC scaffolds.