Branch-Selective Hydroarylation: Iodoarene-Olefin Cross-Coupling

Area of Science:

• Organic Chemistry
• Catalysis
• Reaction Mechanisms

Background:

• Olefin hydroarylation is a crucial reaction in organic synthesis.
• Achieving high regioselectivity, particularly Markovnikov selectivity, remains a challenge.
• Developing efficient catalytic systems is essential for sustainable chemical synthesis.

Purpose of the Study:

• To develop a highly branch-selective (Markovnikov) olefin hydroarylation method.
• To elucidate the catalytic mechanism involving cobalt and nickel.
• To explore the role of radical intermediates in the reaction pathway.

Main Methods:

• Utilized a combined cobalt and nickel catalytic system.
• Investigated reaction pathways through radical cyclization experiments.
• Analyzed reaction intermediates using ring scission experiments.
• Employed hydrogen atom transfer (HAT) to generate carbon-centered radicals.

Main Results:

• Achieved highly branch-selective (Markovnikov) olefin hydroarylation.
• Demonstrated the synergistic action of cobalt and nickel catalytic cycles.
• Provided evidence for hydrogen atom transfer (HAT) initiating the catalytic process.
• Identified the generation of a carbon-centered radical leading to nickel cycle engagement.

Conclusions:

• A novel catalytic system combining cobalt and nickel enables highly Markovnikov-selective olefin hydroarylation.
• The reaction proceeds via a mechanism involving hydrogen atom transfer and subsequent nickel-catalyzed steps.
• This work offers a new strategy for selective C-H functionalization of olefins.