Organoelectrocatalysis Enables Direct Cyclopropanation of Methylene Compounds

Area of Science:

• Organic Chemistry
• Catalysis
• Synthetic Methodology

Background:

• Cyclopropane rings are vital structural motifs in numerous natural products and pharmaceuticals.
• Traditional methods for cyclopropane synthesis often rely on metal catalysts and pre-functionalized substrates like α-diazocarbonyls.
• Direct cyclopropanation from stable methylene compounds remains a significant synthetic challenge.

Purpose of the Study:

• To develop a novel, metal-free electrocatalytic strategy for the synthesis of cyclopropanes.
• To enable cyclopropanation directly from readily available active methylene compounds.
• To provide a safer and more operationally simple alternative to existing methods.

Main Methods:

• Electrocatalysis employing an organic catalyst for cyclopropanation reactions.
• Utilizing active methylene compounds as starting materials.
• Broad substrate scope encompassing various heterocyclic and carbocyclic compounds.

Main Results:

• Successful development of an electrocatalytic cyclopropanation of active methylene compounds.
• Demonstrated broad substrate scope and excellent scalability of the method.
• Achieved synthesis of diverse cyclopropane-fused heterocyclic and carbocyclic compounds without metal catalysts or chemical oxidants.

Conclusions:

• The developed electrocatalytic strategy provides a powerful and sustainable approach for constructing cyclopropane rings.
• The method bypasses the need for transition metals and harsh oxidants, enhancing safety and operational simplicity.
• Mechanistic studies indicate a radical-polar crossover pathway is responsible for the formation of the cyclopropane ring.