Selective Carbocation Functionalization by Catalytic Transchalcogenation Reactions.

Area of Science:

• Organic Chemistry
• Catalysis
• Synthetic Methodology

Background:

• Acid-mediated carbocation chemistry offers a direct route for functionalization but often suffers from poor selectivity and limited applicability.
• Existing methods frequently require toxic reagents, posing safety and environmental concerns.
• A need exists for selective, safe, and broadly applicable methods for introducing sulfur (S) and selenium (Se) functionalities.

Purpose of the Study:

• To develop a novel strategy for the selective and safe introduction of S- and Se-based functionalities into feedstock molecules.
• To overcome the limitations of classical acid-catalyzed carbocation functionalization, particularly regarding selectivity and reagent toxicity.

Main Methods:

• Utilized acid-catalyzed transchalcogenation reactions employing a designable γ-keto donor compound.
• Investigated the formation of a trialkyl chalcogenonium intermediate facilitated by the acid catalyst and its counteranion.
• Explored the elimination pathway of the intermediate to achieve functionalization.

Main Results:

• Successfully demonstrated the selective and safe introduction of small S- and Se-based functionalities.
• Achieved chemo-, regio-, and stereoselective construction of carbon-sulfur (C─S) and carbon-selenium (C─Se) bonds.
• The developed method offers significant advantages in selectivity and safety over traditional carbocation-based functionalization.

Conclusions:

• Acid-catalyzed transchalcogenation provides a powerful and versatile platform for S- and Se-functionalization.
• This methodology represents a significant advancement in synthetic organic chemistry, enabling precise bond formation.
• The strategy offers a safer and more efficient alternative for introducing chalcogen functionalities into organic molecules.