Double Regioselective Thermal Azide-Alkyne Cycloaddition of 1,3-Diynes

Area of Science:

• Organic Chemistry
• Synthetic Chemistry
• Medicinal Chemistry

Background:

• 1,2,3-triazoles are important heterocyclic compounds with broad applications.
• Traditional synthesis methods often require catalysts or harsh conditions.
• Developing efficient and regioselective synthetic routes remains a key challenge.

Purpose of the Study:

• To report a novel, catalyst-free double regioselective cycloaddition reaction.
• To synthesize fully substituted 5-alkynyl-1,2,3-triazoles.
• To investigate the reaction's kinetic and thermodynamic favorability.

Main Methods:

• Reaction of 1,3-diynes with azides.
• Metal-free reaction conditions.
• Computational studies (DFT) to analyze reaction mechanism and stability.

Main Results:

• Achieved synthesis of fully substituted 5-alkynyl-1,2,3-triazoles.
• Demonstrated high regioselectivity without catalysts or metals.
• Computational studies confirmed kinetic and thermodynamic favorability.
• Obtained good to excellent yields across a wide substrate scope.

Conclusions:

• The reported cycloaddition is a simple, efficient, and highly regioselective method for synthesizing 5-alkynyl-1,2,3-triazoles.
• The metal-free conditions and broad applicability make this reaction valuable for organic synthesis.
• This work may stimulate further research into 1,3-diyne cycloadditions and click chemistry alternatives.