Alkyne Origami: Folding Oligoalkynes into Polyaromatics.

Area of Science:

• Organic Chemistry
• Synthetic Chemistry
• Materials Science

Background:

• Alkynes are high-energy, carbon-rich building blocks ideal for creating polyaromatic materials.
• Alkyne reactivity is kinetically hindered by strong pi-bonds, requiring precise control for cyclization.
• Previous guidelines for alkyne cyclizations (2011) analyzed experimental data and computational predictions.

Purpose of the Study:

• To describe the folding of oligoalkynes into new shapes using cyclization cascades ("alkyne origami").
• To demonstrate how stereoelectronic models enable the construction of polyaromatic structures.
• To develop practical, selective, and efficient synthetic transformations for carbon-rich materials.

Main Methods:

• Utilized a set of guidelines for alkyne cyclizations based on experimental research and computational analysis.
• Investigated both "all-exo" and "all-endo" cyclization cascades of oligoynes.
• Employed stereoelectronic factors and topological folding principles to control cyclization pathways.

Main Results:

• Developed a toolbox of synthetic transformations for building polyaromatics with controlled structure and reactivity.
• Highlighted differences between exo and endo cascades, including initiation requirements and stereoelectronic control.
• Introduced strategies like "LUMO Umpolung" and the use of traceless directing groups for selective cyclizations.

Conclusions:

• Stereoelectronic factors and precursor topology are crucial for controlling alkyne cyclization cascades.
• Alkynes can be selectively transformed into precisely shaped polyaromatic products through controlled cyclization.
• The developed methods enable the synthesis of complex carbon-rich materials and functionalized acenes.