Asymmetric Radical-Radical Cross-Coupling through Visible-Light-Activated Iridium Catalysis

Area of Science:

• Organic Chemistry
• Catalysis
• Photochemistry

Background:

• 1,2-amino alcohols are crucial building blocks in pharmaceuticals.
• Existing synthetic methods often lack stereocontrol or require harsh conditions.

Purpose of the Study:

• To develop a visible-light-driven catalytic method for enantioselective synthesis of 1,2-amino alcohols.
• To utilize single electron transfer and radical-radical recombination for C-C bond formation.
• To achieve high stereocontrol using a chiral iridium complex.

Main Methods:

• Visible-light photocatalysis with a chiral iridium complex.
• Single electron transfer from a donor to an acceptor substrate.
• Stereocontrolled radical-radical recombination.
• Enantioselective synthesis using trifluoromethyl ketones and tertiary amines.

Main Results:

• High yields and excellent enantioselectivities (up to 99% ee) and diastereoselectivities were achieved.
• The chiral iridium complex functioned as both a Lewis acid and a photoredox catalyst.
• A quantum yield of <1 supported the proposed catalytic cycle.

Conclusions:

• The developed method offers an efficient and stereoselective route to valuable 1,2-amino alcohols.
• This approach highlights the potential of visible-light photocatalysis in asymmetric synthesis.
• The catalytic cycle involves single electron transfer and is photon-efficient for asymmetric C-C bond formation.