Photocatalyzed Aryl C-H Fluorocarbonylation with CF₂Br₂

Area of Science:

• Organic Chemistry
• Fluorine Chemistry
• Catalysis

Background:

• Synthesizing fluorinated compounds is crucial but often relies on expensive or underexplored fluorine sources.
• Dibromodifluoromethane (CF2Br2) is an inexpensive and abundant fluorine feedstock with limited application in C-H fluoroalkylation.
• Developing efficient methods for incorporating fluorine into organic molecules is a key challenge in synthetic chemistry.

Purpose of the Study:

• To develop a novel iridium-catalyzed strategy for C-H fluoroalkylation using dibromodifluoromethane (CF2Br2).
• To demonstrate a tunable synthetic approach for accessing acyl fluorides and difluorobromomethylated products.
• To explore the scope and limitations of the new methodology with various arene and heteroarene substrates.

Main Methods:

• Iridium-catalyzed C-H functionalization reaction.
• Utilizing dibromodifluoromethane (CF2Br2) as the fluorine source.
• Employing blue LED irradiation and varying solvents (DMSO, 1,4-dioxane) to control product formation.
• Investigating mechanistic pathways through experimental studies.

Main Results:

• Successful synthesis of acyl fluorides and difluorobromomethylated products via C-H fluoroalkylation.
• The reaction outcome (acyl fluoride vs. difluorobromomethylation) is tunable by changing the solvent.
• A variety of electron-rich arenes and heteroarenes were effectively functionalized in moderate to good yields.
• Mechanistic studies indicated DMSO acts as both a solvent and a nucleophilic reagent in C-H fluorocarbonylation.

Conclusions:

• An efficient and tunable iridium-catalyzed C-H fluoroalkylation method using dibromodifluoromethane (CF2Br2) has been established.
• The developed strategy offers a cost-effective route to valuable fluorinated organic compounds.
• The dual role of DMSO as solvent and reagent in the C-H fluorocarbonylation process was elucidated.