Radical-Polar Crossover Annulation: A Platform for Accessing Polycyclic Cyclopropanes.

Area of Science:

• Organic Chemistry
• Synthetic Methodology
• Photocatalysis

Background:

• Radical/polar crossover (RPC) processes offer novel synthetic strategies.
• Cyclopropanation of bicyclic olefins is synthetically challenging using traditional methods.

Purpose of the Study:

• To develop a photoredox-mediated RPC approach for the cyclopropanation of bicyclic olefins.
• To synthesize complex polycarbocyclic and polyheterocyclic cyclopropanes.

Main Methods:

• Utilizing photoredox catalysis to initiate radical formation.
• Employing a Giese-type radical addition mechanism.
• Leveraging intramolecular anionic substitution on a neopentyl leaving group.

Main Results:

• Successful cyclopropanation of olefins within bicyclic scaffolds.
• Efficient synthesis of polycarbocyclic and polyheterocyclic cyclopropanes.
• Demonstration of RPC cyclopropanation's ease compared to classical methods.

Conclusions:

• Photoredox-mediated RPC is a powerful tool for challenging cyclopropanations.
• This methodology provides access to complex cyclic structures.
• The developed approach overcomes limitations of classical cyclopropanation techniques.