Helical Topologies via [4 + 2] Cycloaddition Reactions between Structurally Complex Benzynes and Several Alkenyl...

Area of Science:

• Organic Chemistry
• Synthetic Chemistry
• Polycyclic Aromatic Hydrocarbons

Background:

• Vinyl-substituted arenes and benzynes are key building blocks in organic synthesis.
• Hexadehydro-Diels-Alder (HDDA) reactions offer pathways to complex molecular architectures.
• Understanding the reactivity of dearomatized adducts is crucial for developing new synthetic methodologies.

Purpose of the Study:

• To investigate the reactions of various vinyl-substituted arenes with benzynes.
• To explore the formation of complex polycyclic products with helical topologies.
• To elucidate the mechanistic pathways and reactivity of the initial adducts.

Main Methods:

• Generation of benzynes via thermal cycloisomerization of triyne substrates using hexadehydro-Diels-Alder (HDDA) reaction.
• Reaction of in-situ generated benzynes with vinyl-substituted arenes (phenyl, 2-naphthyl, 9-phenanthryl, 2-triphenylenyl).
• Exploration of reactions involving indene and benzofuran.

Main Results:

• Formation of structurally complex, polycyclic products with helical topologies.
• Observation of unexpected reactivity modes in initial [4 + 2] dearomatized adducts, including ene reactions, [2 + 2] cycloadditions, and autoxidation.
• Demonstration of significant complexity-building, with up to five new rings formed in some cases.
• Identification of fully atom-economical transformations.

Conclusions:

• The reaction of vinyl-substituted arenes with benzynes provides access to intricate polycyclic molecules with helical structures.
• The observed reactivity highlights novel mechanistic pathways and the potential for cascade reactions.
• These findings contribute to the development of efficient and atom-economical synthetic strategies for complex molecule construction.