Merging Carbonyl Addition with Photocatalysis

Area of Science:

• Organic Chemistry
• Photocatalysis
• Radical Chemistry

Background:

• Carbonyl groups are central to many chemical reactions, but traditional methods have limitations.
• Two-electron mechanisms restrict the scope of accessible reactivity and molecular structures.
• Photoredox catalysis offers new avenues for sustainable chemical transformations.

Purpose of the Study:

• To develop novel synthetic strategies utilizing carbonyl compounds as radical acceptors.
• To expand the reactivity of carbonyl chemistry through photoredox catalysis.
• To enable the synthesis of complex molecular motifs previously inaccessible.

Main Methods:

• Visible-light photoredox-initiated hole catalysis for radical addition to carbonyls.
• In situ Brønsted acid activation to prevent undesirable side reactions.
• Dual chromium and photoredox catalysis for radical-to-polar crossover reactions.
• Photocatalytic hydrogen atom transfer for acyl radical formation.

Main Results:

• Developed a regioselective alkyl radical addition to carbonyls without metals or additives, achieving high atom economy.
• Achieved visible-light-induced carbonyl-olefin cross-metathesis via a radical Prins-elimination sequence.
• Demonstrated dual catalysis for redox-neutral allylation and radical carbonyl alkylation with high diastereoselectivity.
• Enabled carbonyl alkynylation and trifluoromethylthiolation using photocatalytic acyl radical generation.

Conclusions:

• Photoredox catalysis combined with radical chemistry significantly expands carbonyl reactivity.
• Novel methods provide sustainable and efficient access to valuable molecular structures.
• Future directions include exploring less-activated carbonyls and multicomponent reactions.