A Catalyst-Free Three-Component Approach to Sulfonated Indole-Fused Diazepinones via SO₂ Insertion.

Area of Science:

• Organic Synthesis
• Medicinal Chemistry
• Green Chemistry

Background:

• Indole-fused 1,4-diazepinones are important heterocyclic scaffolds.
• Developing efficient and sustainable synthetic methods is crucial for accessing diverse chemical structures.
• Catalyst-free reactions minimize environmental impact and simplify purification.

Purpose of the Study:

• To establish a green, efficient, and environmentally benign synthetic strategy.
• To prepare diverse sulfonated indole-fused 1,4-diazepinones.
• To explore catalyst-free multicomponent radical annulation for seven-membered heterocycle synthesis.

Main Methods:

• Catalyst-free multicomponent radical annulation.
• Radical cyclization reactions.
• Synthesis of sulfonated indole-fused seven-membered diazepinones.

Main Results:

• Achieved a green and efficient synthetic strategy.
• Prepared diverse sulfonated indole-fused 1,4-diazepinones.
• Obtained high yields (up to >99%) and excellent diastereoselectivity (up to >20:1 dr).
• Demonstrated direct access to sulfonated indole-fused seven-membered diazepinones.

Conclusions:

• The developed protocol is a valuable addition to synthetic organic chemistry.
• This method provides a sustainable and efficient route to important heterocyclic compounds.
• The reaction's mild conditions and broad scope make it widely applicable.