Synthetic Transformations through Alkynoxy-Palladium Interactions and C-H Activation.

Area of Science:

• Organic Chemistry
• Catalysis
• Sustainable Synthesis

Background:

• Metal-catalyzed C-H functionalization is key for sustainable synthesis.
• Directing groups are crucial for site-selective C-H bond cleavage.
• Unsaturated bonds are underexplored as directing groups.

Purpose of the Study:

• To develop novel C-H activation methods using the alkynoxy group.
• To explore the dual role of the alkynoxy group as a directing and accepting moiety.
• To synthesize valuable π-conjugated systems through C-H functionalization.

Main Methods:

• Palladium-catalyzed C-H activation of alkynyl aryl ethers.
• Utilizing the alkynoxy group for ortho-C-H bond activation.
• Sequential insertion/annulation reactions with various unsaturated partners.

Main Results:

• Demonstrated palladium's interaction with the alkynoxy group for C-H cleavage.
• Synthesized 2-methylidene-2H-1-benzopyrans via ortho-C-H activation and annulation.
• Produced benzofurans and dibenzopyrans through intramolecular annulation.

Conclusions:

• The alkynoxy group effectively directs palladium-catalyzed C-H activation.
• This methodology provides a straightforward route to diverse oxacycles and π-conjugated systems.
• The developed reactions contribute to environmentally benign organic synthesis.