Catalyst- and Reagent-Free Formal Aza-Wacker Cyclizations Enabled by Continuous-Flow Electrochemistry

Area of Science:

• Organic Chemistry
• Synthetic Methodology
• Green Chemistry

Background:

• Saturated N-heterocycles are crucial scaffolds in natural products and pharmaceuticals.
• Palladium-catalyzed aza-Wacker cyclization is a known method for N-heterocycle synthesis but requires catalysts and reagents.
• Developing sustainable and efficient synthetic routes is paramount in modern chemistry.

Purpose of the Study:

• To develop a catalyst- and reagent-free method for synthesizing functionalized saturated N-heterocycles.
• To explore the utility of continuous-flow electrochemistry for aza-Wacker type cyclizations.
• To establish a sustainable and efficient alternative to traditional synthetic approaches.

Main Methods:

• Utilized a continuous-flow electrochemical reactor.
• Performed a formal aza-Wacker type cyclization without supporting electrolytes or additives.
• Investigated the reaction's tolerance to various alkene substitutions (di-, tri-, and tetrasubstituted).

Main Results:

• Successfully synthesized functionalized saturated N-heterocycles.
• Demonstrated a catalyst- and reagent-free process.
• Showcased broad substrate scope, accommodating diverse alkene structures.

Conclusions:

• Continuous-flow electrochemistry offers a powerful and sustainable platform for N-heterocycle synthesis.
• The developed method provides an efficient, additive-free route to valuable heterocyclic compounds.
• This approach represents a significant advancement in green synthetic chemistry.