Building Catalytic Reactions One Electron at a Time.

Area of Science:

• Organic Chemistry
• Catalysis
• Synthetic Methodology

Background:

• Traditional organic chemistry and catalysis heavily rely on two-electron transformations.
• Nature's enzymes utilize single-electron radical steps for high selectivity in complex reactions.
• The development of outer-sphere photoredox catalysis highlights the potential of radical chemistry.

Purpose of the Study:

• To expand the scope of synthetic radical catalysis beyond established methods.
• To explore new catalytic cycles combining hydrogen atom transfer (HAT) and light-induced homolysis (LIH) steps.
• To demonstrate the application of these radical steps in challenging chemical transformations using iron/thiol (Fe/S) cocatalysis.

Main Methods:

• Investigated combinations of hydrogen atom transfer (HAT) and light-induced homolysis (LIH) radical elementary steps.
• Employed iron/thiol (Fe/S) cocatalysis as a flexible catalytic system.
• Utilized three case studies: radical hydrogenation, decarboxylative protonation, and alkene hydrofluoroalkylation.

Main Results:

• Successfully developed new catalytic reactions by combining HAT and LIH steps.
• Demonstrated the utility of Fe/S cocatalysis for radical transformations.
• Highlighted the importance of bond dissociation energy (BDE) and radical polarity in reaction design.

Conclusions:

• Radical elementary steps, including HAT and LIH, offer powerful complementary approaches to traditional two-electron chemistry.
• Fe/S cocatalysis provides a versatile platform for developing novel radical catalytic cycles.
• Understanding key parameters like BDE and radical polarity is crucial for designing new radical catalytic reactions.