A highly selective cascade approach to diverse aromatic ring systems from simple aromatic aldehydes and propiolates

Area of Science:

• Organic Chemistry
• Catalysis
• Synthetic Methodology

Background:

• Polycyclic aromatic hydrocarbons (PAHs) are crucial structural motifs in materials science and medicinal chemistry.
• Efficient and selective synthetic routes to diverse PAHs remain a significant challenge in organic synthesis.

Purpose of the Study:

• To develop a novel cascade reaction for the synthesis of various polycyclic aromatic hydrocarbons.
• To investigate the influence of reaction conditions, specifically temperature, on the outcome of the cascade process.
• To demonstrate the selective formation of different PAH scaffolds, including naphthalenes, phenanthrenes, benzofurans, and tetrahydronaphthofurans.

Main Methods:

• A new triethylamine-catalyzed cascade reaction involving aromatic aldehydes and propiolates was employed.
• The reaction was systematically studied at different temperatures to observe variations in product distribution.
• Characterization of the synthesized polycyclic aromatic hydrocarbons was performed using standard spectroscopic techniques.

Main Results:

• A novel serial multi-bond-forming cascade reaction was successfully developed.
• The reaction provides access to a diverse range of polycyclic aromatic hydrocarbons, including naphthalenes, phenanthrenes, and benzofurans.
• Product selectivity, yielding specific PAH structures like 2,3,9,9a-tetrahydronaphtha[2,3-b]furans, was achieved by controlling the reaction temperature.

Conclusions:

• A versatile and efficient triethylamine-catalyzed cascade reaction has been established for PAH synthesis.
• The reaction offers a temperature-dependent pathway to selectively generate different classes of polycyclic aromatic hydrocarbons.
• This methodology provides a valuable tool for the targeted synthesis of complex PAH structures.