Substrate-Affinitive P-Type Azapolycyclic Photosensitizer for Chemoselective Nitrilization Under Mild Conditions

Area of Science:

• Organic Chemistry
• Photochemistry
• Materials Science

Background:

• Development of efficient photosensitizers is crucial for catalytic organic transformations.
• Mild and scalable methods for converting amides to nitriles are highly sought after in synthetic chemistry.

Purpose of the Study:

• To introduce novel azapolycyclic quinoxalinoquinoxaline (QQ) photosensitizers.
• To demonstrate their utility in catalyzing the direct nitrilization of primary amides under mild conditions.
• To explore their potential in semiconductor applications.

Main Methods:

• Synthesis of QQ-Ar photosensitizers on a gram scale.
• Purification via vacuum sublimation.
• Catalytic conversion of various primary amides to nitriles using QQ photosensitizers.
• Spectroscopic and computational studies to elucidate the reaction mechanism.

Main Results:

• QQ-Ar photosensitizers exhibit tunable reducing ability and strong excited-state reduction potentials.
• Facile synthesis and purification via vacuum sublimation enable semiconductor applications.
• Direct nitrilization of a wide range of primary amides, including pharmaceutical derivatives, achieved under mild conditions with high functional group tolerance.
• Mechanism involves oxidative quenching and selective hydrogen atom abstraction.

Conclusions:

• QQ photosensitizers represent a practical and versatile platform for amide-to-nitrile conversions.
• The developed method offers mild conditions, high functional group tolerance, and scalability for industrial and synthetic applications.
• The properties of QQ photosensitizers also suggest potential utility in vapor-phase deposition for semiconductor applications.