HFIP-Promoted Regioselective Hydrofunctionalization of Enamides and N-Vinyl Azoles

Area of Science:

• Organic Chemistry
• Synthetic Methodology
• Catalysis

Background:

• Intermolecular hydrofunctionalization is crucial for synthesizing complex organic molecules.
• Existing methods often require transition metals, harsh additives, or strong acids, limiting their scope and sustainability.
• Developing metal-free and additive-free protocols is highly desirable for greener synthetic chemistry.

Purpose of the Study:

• To develop an efficient and regioselective intermolecular hydrofunctionalization protocol for enamides and N-vinyl azoles.
• To achieve the formation of diverse C-S, C-O, C-N, and C-C bonds using a single reagent.
• To establish a transition-metal-free, additive-free, and Brønsted acid-free reaction system.

Main Methods:

• Utilizing hexafluoroisopropanol (HFIP) as the sole reagent for hydrofunctionalization.
• Employing HFIP's dual role in forming iminium carbocation intermediates and facilitating nucleophile generation via hydrogen bonding.
• Investigating the reaction's scope with various nucleophiles including thiophenols, alcohols, heterocyclic amines, and NH-free indoles, pyrroles, and carbazoles.

Main Results:

• Successful development of a regioselective intermolecular hydrofunctionalization of enamides and N-vinyl azoles.
• Demonstrated formation of diverse C-S, C-O, C-N, and C-C bonds under transition-metal-free, additive-free, and Brønsted acid-free conditions.
• Achieved broad substrate compatibility and high versatility with a wide range of nucleophiles and substrates, proceeding via Markovnikov selectivity.

Conclusions:

• The developed protocol offers an efficient, general, and simple method for intermolecular hydrofunctionalization.
• Hexafluoroisopropanol (HFIP) acts as a versatile reagent, enabling metal-free and additive-free C-X and C-C bond formation.
• This approach provides a sustainable and broadly applicable strategy for synthesizing valuable organic compounds.