Ligand-Enabled Meta-C-H Alkylation and Arylation Using a Modified Norbornene

Area of Science:

• Organic Chemistry
• Catalysis

Background:

• Palladium-catalyzed C-H functionalization is a powerful tool in organic synthesis.
• Developing efficient methods for meta-C(sp2)-H functionalization of amides remains challenging.

Purpose of the Study:

• To identify effective transient mediators for palladium-catalyzed meta-C(sp2)-H alkylation and arylation of amides.
• To develop a robust catalytic system for previously incompatible coupling partners.

Main Methods:

• Utilizing 2-carbomethoxynorbornene as a transient mediator.
• Employing a tailor-made quinoline ligand in Pd(II)-catalyzed reactions.
• Screening various alkyl and aryl iodides for coupling with amides.

Main Results:

• 2-Carbomethoxynorbornene demonstrated superior performance as a transient mediator.
• The catalytic system successfully promoted meta-C(sp2)-H alkylation with diverse alkyl iodides.
• The reaction enabled arylation using aryl iodides that were previously incompatible with such transformations.
• The custom quinoline ligand was essential for achieving high efficiency and selectivity.

Conclusions:

• 2-Carbomethoxynorbornene is a highly effective transient mediator for Pd-catalyzed meta-C(sp2)-H functionalization of amides.
• The developed methodology expands the scope of C-H alkylation and arylation, including challenging substrates.
• The combination of the mediator and the specialized ligand offers a valuable advancement in synthetic organic chemistry.