Visible Light-Induced Ligation via o-Quinodimethane Thioethers

Area of Science:

• Organic Chemistry
• Polymer Chemistry
• Photochemistry

Background:

• Photocaged dienes are valuable tools in organic synthesis.
• Existing methods often require UV light and specific conditions.
• There is a need for more versatile and accessible photocaged systems.

Purpose of the Study:

• To introduce a novel photocaged diene system based on o-methylbenzaldehydes (o-MBAs).
• To demonstrate visible light activation for Diels-Alder reactions and polymer ligation.
• To establish a versatile and efficient orthogonal ligation platform.

Main Methods:

• Synthesis of o-quinodimethane thioethers from o-MBAs.
• Visible light-mediated Diels-Alder reactions with maleimides under flow conditions.
• Demonstration of polymer block ligation using the photocaged diene system.

Main Results:

• The photocaged diene system is synthesized in a single step with excellent yields.
• Visible light irradiation triggers catalyst-free Diels-Alder reactions in organic and aqueous solutions.
• Successful ligation of two polymer blocks was achieved, showcasing its utility.
• The reaction proceeds efficiently under LED irradiation in flow conditions.

Conclusions:

• The developed photocaged diene system offers a user-friendly and efficient approach for chemical synthesis.
• Visible light activation provides a milder and more versatile alternative to UV-induced methods.
• This platform enables powerful orthogonal ligation strategies for complex molecule and polymer assembly.