Cross-Dimerization Giving Silyl-Substituted Conjugated Hexatrienes: An Approach to 1,6-Diarylhexa-1,3,5-trienes.

Area of Science:

• Organic Synthesis
• Organometallic Chemistry
• Materials Science

Background:

• 1,6-diarylhexa-1,3,5-trienes (DAHs) are valuable organic compounds with unique photophysical properties.
• Efficient synthetic routes to DAHs are crucial for exploring their potential applications.

Purpose of the Study:

• To develop a novel synthetic strategy for constructing 1,6-diarylhexa-1,3,5-trienes (DAHs).
• To investigate the stereochemical outcomes and reaction mechanisms involved in the synthesis.
• To characterize the photophysical properties of the newly synthesized DAHs.

Main Methods:

• Ruthenium-catalyzed cross-dimerization of 1-aryl-2-silylethyne and benzyl((E)-buta-1,3-dien-1-yl)dimethylsilane.
• Palladium-catalyzed Hiyama cross-coupling reaction with aryl iodides.
• X-ray crystallography for structural determination.
• Photochemical studies and TD-DFT calculations for photophysical analysis.

Main Results:

• A new synthetic route to (1E,3E,5E)-1,6-diarylhexa-1,3,5-trienes (DAHs) was successfully established.
• The synthesis involves a sequential ruthenium- and palladium-catalyzed process, demonstrating control over stereochemistry.
• The synthesized DAHs exhibit bright fluorescence with a large Stokes shift, attributed to π-π* transitions.

Conclusions:

• The developed method provides an efficient access to a range of (1E,3E,5E)-1,6-diarylhexa-1,3,5-trienes (DAHs).
• The study elucidates the reaction mechanism, including the stereochemical control and the role of protodesilylation.
• The fluorescent properties of the new DAHs suggest their potential utility in optoelectronic applications.