Extension of antiaromatic norcorrole by cycloaddition

Area of Science:

• Organic Chemistry
• Porphyrinoid Chemistry
• Supramolecular Chemistry

Background:

• Norcorroles are contracted tetrapyrrolic porphyrinoids with antiaromatic character.
• Understanding the reactivity and properties of norcorrole derivatives is crucial for developing new functional materials.

Purpose of the Study:

• To investigate the [2+3] dipolar cycloaddition of iminonitriles to the antiaromatic ring of norcorrole.
• To characterize the resulting chiral chlorins and their subsequent transformation products.
• To evaluate the impact of these transformations on the electronic properties, specifically paratropicity.

Main Methods:

• Synthesis of norcorrole derivatives.
• [2+3] dipolar cycloaddition reactions using iminonitriles.
• Dehydrogenation of chlorin intermediates.
• Spectroscopic characterization (NMR, UV-Vis, etc.).
• Computational studies to assess paratropicity.

Main Results:

• Successful [2+3] dipolar cycloaddition of iminonitriles to norcorrole was achieved.
• The resulting chiral chlorins maintained the paratropic character of the norcorrole precursor.
• Dehydrogenation of the chlorins in air yielded pyrazole-fused norcorroles.
• The pyrazole-fused norcorroles exhibited significantly enhanced paratropicity compared to the starting materials.

Conclusions:

• The [2+3] cycloaddition provides a viable route to functionalize norcorroles.
• The developed methodology allows for the synthesis of novel pyrazole-fused norcorrole systems.
• These new compounds possess enhanced paratropicity, suggesting potential applications in areas sensitive to electronic properties.