Meso-Substituted Corroles from Nitrosoalkenes and Dipyrromethanes

Area of Science:

• Organic Chemistry
• Synthetic Chemistry
• Macrocyclic Chemistry

Background:

• Pyrrole-containing macrocycles like corroles and porphyrins are crucial in various chemical and biological processes.
• Efficient synthetic routes to novel macrocyclic structures are essential for expanding their applications.
• Hetero-Diels-Alder reactions offer a powerful tool for constructing complex organic frameworks.

Purpose of the Study:

• To describe the synthesis of novel bilanes and hexapyrroles incorporating an oxime functionality.
• To explore the transformation of these precursors into new classes of corroles and porphyrins.
• To establish efficient synthetic methodologies utilizing hetero-Diels-Alder reactions.

Main Methods:

• Two and three consecutive hetero-Diels-Alder reactions (or conjugated additions) between nitrosoalkenes and dipyrromethanes were employed for precursor synthesis.
• Oxidative macrocyclization of bilanes to yield trans-A₂B-corroles.
• Reaction of bilanes with aldehydes in the presence of trifluoroacetic acid, followed by oxidation, to produce porphyrins.

Main Results:

• Successful synthesis of bilanes and hexapyrroles featuring an oxime group.
• Formation of a new class of trans-A₂B-corroles via oxidative macrocyclization of the synthesized bilanes.
• Generation of porphyrins from bilanes using aldehyde condensation and subsequent oxidation.

Conclusions:

• A novel synthetic strategy for accessing bilanes and hexapyrroles has been developed.
• The study demonstrates the utility of these precursors in constructing new trans-A₂B-corroles and porphyrins.
• The described methods provide versatile routes to important macrocyclic compounds.