Enforced Electronic-Donor-Acceptor Complex Formation in Water for Photochemical Cross-Coupling

Area of Science:

• Organic Photochemistry
• Supramolecular Chemistry
• Synthetic Organic Chemistry

Background:

• Traditional organic solvents limit the formation of specific electron donor-acceptor (EDA) complexes.
• Certain organic compounds, like haloarenes and indoles, do not readily form EDA complexes in common organic media.
• Novel activation modes are needed for efficient photochemical synthesis.

Purpose of the Study:

• To investigate the role of the amino alcohol meglumine in facilitating EDA complex formation in aqueous media.
• To explore UV-A photoinduced electron transfer within these enforced EDA complexes for novel cross-coupling reactions.
• To demonstrate new activation modes for organic photochemical synthesis in water.

Main Methods:

• Utilized UV-A irradiation and Nuclear Magnetic Resonance (NMR) spectroscopy to study reaction mechanisms.
• Employed meglumine as a solubilizing agent and complexation promoter in water.
• Investigated cross-coupling reactions between haloarenes and electron-rich compounds (indoles, anilines, anisoles, thiols).

Main Results:

• Meglumine successfully enforced the formation of EDA complexes in water, which are not observed in organic solvents.
• Photoinduced electron transfer within these complexes led to mesolytic cleavage and subsequent C-C or C-S coupling products.
• Selective and unique cross-coupling reactions were achieved, dependent on substrate substitution patterns.

Conclusions:

• Enforced EDA aggregate formation in water using meglumine provides a novel platform for organic photochemical synthesis.
• This approach enables new activation modes, overcoming limitations of traditional organic solvents.
• The study highlights the potential of aqueous photochemical reactions for generating complex organic molecules.