Rational Design of an Organotellurium Chalcogen Bonding Catalyst for Azetidine Activation

Area of Science:

• Organic Chemistry
• Catalysis
• Supramolecular Chemistry

Background:

• Chalcogen bonding catalysis, particularly using tellurium, has faced limitations due to scarce catalyst diversity and activity.
• Existing tellurium-based catalysts are primarily used in benchmark reactions, restricting broader applications.

Purpose of the Study:

• To develop novel bis-telluronium catalysts for enhanced chalcogen bonding applications.
• To achieve the first catalytic [4+2] cycloaddition reaction utilizing chalcogen bonding donors with azetidines and non-activated cyclic/acyclic alkenes or alkynes.
• To synthesize valuable piperidine and tetrahydropyridine derivatives.

Main Methods:

• Rational design and synthesis of bis-telluronium compounds.
• Catalysis of [4+2] cycloaddition reactions between azetidines and various alkenes/alkynes.
• Mechanistic studies including experimental investigations and Density Functional Theory (DFT) calculations.

Main Results:

• Successful application of designed bis-telluronium catalysts in promoting [4+2] cycloaddition reactions.
• Demonstration of excellent functional group tolerance and moderate-to-good yields for piperidine and tetrahydropyridine products.
• Identification of a novel bidentate activation mechanism involving Te-O interaction, supported by mechanistic experiments and DFT analysis.

Conclusions:

• The developed organotellurium catalysts exhibit high activity, attributed to electron-deficient aromatic substituents.
• This work expands the scope of chalcogen bonding catalysis to include challenging cycloaddition reactions.
• A new catalytic activation mode via Te-O interaction has been proposed, advancing the understanding of tellurium-mediated catalysis.