Carbofunctionalization of Terminal Alkynes via Rhodium Catalysis Enabling Formations of Four Different Bonds

Area of Science:

• Organic Chemistry
• Catalysis
• Synthetic Methodology

Background:

• Terminal alkynes are versatile building blocks in organic synthesis.
• Developing efficient methods for carbofunctionalization remains a key challenge.
• Rhodium catalysis offers unique reactivity for C-H and C-C bond formation.

Purpose of the Study:

• To develop a novel rhodium-catalyzed oxygenative carbofunctionalization of terminal alkynes.
• To achieve regioselective formation of multiple bonds (C-C, C-H, C-O, C-heteroatom).
• To synthesize diverse cyclic carboxylic acid derivatives.

Main Methods:

• Combined rhodium catalysis for alkyne functionalization.
• Use of tethered electrophiles (alkyl halides, aldehydes, imines, Michael acceptors).
• Intermolecular transfer oxygenation using pyridine N-oxide.
• Reaction with various heteroatom nucleophiles.

Main Results:

• Regioselective quadruple bond formation (C-C, C-H, C-O, C-heteroatom) achieved.
• Generation of a rhodium vinylidene intermediate.
• Formation of a rhodium-ketene intermediate via oxygenation.
• Synthesis of cyclic carboxylic acid derivatives from diverse nucleophiles.

Conclusions:

• The developed method provides a powerful route for synthesizing cyclic carboxylic acid derivatives.
• The rhodium-catalyzed oxygenative carbofunctionalization offers a new strategy in synthetic organic chemistry.
• Mechanistic insights into vinylidene and ketene intermediates were obtained.