Intramolecular Fluoroacylation Enabled by TrBF₄-Catalyzed Fluoride Recycling

Area of Science:

• Organic Chemistry
• Fluorine Chemistry
• Catalysis

Background:

• Intramolecular carbofluorination is a key transformation for accessing fluorinated molecules.
• Existing methods often rely on expensive metal catalysts and harsh reaction conditions.
• Developing efficient and selective methods for C-F bond formation remains a significant challenge.

Purpose of the Study:

• To develop a novel catalytic system for intramolecular carbofluorination.
• To achieve high stereoselectivity in the synthesis of fluorinated cyclic compounds.
• To provide a more sustainable and cost-effective alternative to existing protocols.

Main Methods:

• Utilized alkyne- and alkene-tethered acyl fluorides as substrates.
• Employed catalytic amounts of TrBF4 (Scandium triflate) for fluoride recycling.
• Investigated the stereoselectivity of the carbofluorination reaction.

Main Results:

• Achieved efficient intramolecular carbofluorination via fluoride recycling.
• Demonstrated excellent stereoselectivity for alkyne additions, yielding fluorinated indan-2-ones (≥95:5 E/Z) and cyclopentan-2-ones (85:15 E/Z).
• Successfully synthesized fluorinated chroman-2-ones and tertiary alkyl fluorides.

Conclusions:

• The developed TrBF4-catalyzed method offers a highly stereoselective and efficient route to valuable fluorinated compounds.
• This protocol provides a greener and more economical alternative compared to traditional methods.
• The fluoride recycling strategy enhances sustainability and reduces catalyst loading.