Visible light-induced reductive aza-6π electrocyclization access to phenanthridines.

Area of Science:

• Organic Chemistry
• Photochemistry
• Synthetic Methodology

Background:

• Aza-arenes are important heterocyclic compounds with diverse applications.
• Efficient synthesis of substituted phenanthridines remains a challenge in organic chemistry.

Purpose of the Study:

• To develop a novel visible light-induced protocol for synthesizing aza-arenes.
• To construct diverse 6- and multi-substituted phenanthridines from readily available nitroarenes and aldehydes.

Main Methods:

• Visible light-induced aza-6π electrocyclization.
• Reduction of nitroarenes using bis(neopentyl glycolato)diboron (B2nep2).
• In situ imine formation followed by photoredox catalysis.

Main Results:

• Successful synthesis of various 6- and multi-substituted phenanthridines.
• Moderate to good yields achieved under mild conditions (room temperature, purple LEDs).
• Broad substrate scope tolerating diverse functional groups.

Conclusions:

• The developed protocol offers an efficient and versatile route to substituted phenanthridines.
• The methodology demonstrates potential for late-stage functionalization in complex molecule synthesis, as shown with celecoxib.