Hemicryptophane Cages with a C₁-Symmetric Cyclotriveratrylene Unit

Area of Science:

• Supramolecular Chemistry
• Organic Synthesis
• Crystal Engineering

Background:

• Hemicryptophanes are molecular cages with potential applications in molecular recognition and catalysis.
• Achieving specific symmetries, like C3, is often a target in hemicryptophane synthesis for predictable host-guest chemistry.

Purpose of the Study:

• To synthesize novel hemicryptophanes by combining a cyclotriveratrylene (CTV) unit with specific amine moieties.
• To investigate the structural properties and symmetry of the newly synthesized molecular cages.
• To explore an alternative synthetic route for accessing low-symmetry chiral molecular cages.

Main Methods:

• Synthesis of hemicryptophanes via conventional organic chemistry methods.
• Nuclear Magnetic Resonance (NMR) spectroscopy for structural elucidation.
• X-ray crystallography for precise determination of molecular structure and symmetry.

Main Results:

• Two new hemicryptophanes were successfully synthesized, incorporating CTV with aminotrisamide or tris(2-aminoethyl)amine (tren) groups.
• The synthesized hemicryptophanes unexpectedly displayed C1 symmetry instead of the anticipated C3 symmetry.
• Structural analysis revealed an unusual arrangement of CTV substituents, attributed to altered regioselectivity in Friedel-Crafts reactions.

Conclusions:

• The study presents an original approach to creating enantiopure chiral molecular cages with low symmetry.
• The findings highlight the impact of regioselectivity in Friedel-Crafts reactions on the final symmetry of molecular cages.
• This work expands the toolkit for designing structurally diverse and asymmetric supramolecular architectures.