Visible-Light-Driven Germyl Radical Generation via EDA-Catalyzed ET-HAT Process

Area of Science:

• Organic Chemistry
• Photochemistry
• Radical Chemistry

Background:

• Generation of germyl and silyl radicals is crucial for various synthetic transformations.
• Existing methods often require harsh conditions or expensive catalysts.
• Developing milder and more efficient radical generation protocols is an ongoing challenge.

Purpose of the Study:

• To establish a facile and efficient protocol for generating germyl radicals.
• To explore the use of photo-induced electron transfer in radical generation.
• To demonstrate the applicability of the protocol for silyl radical generation.

Main Methods:

• Utilizing an electron donor-acceptor (EDA) complex formed from commercially available thiol and benzophenone derivatives.
• Employing blue-light irradiation to initiate photo-excited electron transfer (ET).
• Driving hydrogen-atom transfer (HAT) from germyl hydride (R3GeH) using the ET-HAT cycle.

Main Results:

• Successfully generated germyl radicals via a catalytic ET-HAT cycle.
• The protocol operates efficiently under blue-light irradiation.
• No transition metal or external photocatalyst was required.
• The method was also effective in generating silyl radicals from silyl hydride.

Conclusions:

• A novel and efficient protocol for germyl and silyl radical generation has been established.
• The method relies on photo-induced electron transfer within an EDA complex.
• This approach offers a metal-free and photocatalyst-free alternative for radical synthesis.