Novel route to functionalized cyclooctanoids via [5+3] cycloaddition.

Area of Science:

• Organic Chemistry
• Supramolecular Chemistry

Background:

• 3-oxidopyrylium compounds are versatile synthons.
• Cyclooctanoid structures are challenging to synthesize stereoselectively.

Purpose of the Study:

• To describe the self-dimerization of 3-oxidopyrylium.
• To explore stereocontrolled synthesis of functionalized cyclooctanoids.
• To investigate the influence of reaction conditions on product formation.

Main Methods:

• Self-dimerization reaction of 3-oxidopyrylium.
• Functionalization of the resulting dimer.
• Single-crystal X-ray diffraction for stereochemical determination.
• Hydrogenation reactions under varying solvent conditions.

Main Results:

• Stereocontrolled formation of highly functionalized cyclooctanoids from 3-oxidopyrylium dimerization.
• Successful introduction of diverse functionalities onto the dimer.
• Solvent-dependent outcomes in hydrogenation: transannulated product 5 in ethanol, dihydro product 4 in nonnucleophilic solvents.
• Elucidation of the mechanistic pathway.

Conclusions:

• 3-oxidopyrylium self-dimerization is an effective route to complex cyclooctanoids.
• Reaction conditions, particularly solvent choice, critically control stereochemical outcomes.
• The study provides insights into the mechanism of these transformations.