An Eco-friendly Approach to C-H Bond Activation through Microwave Irradiation Employing Synthesized...

Area of Science:

• Organic Chemistry
• Catalysis
• Green Chemistry

Background:

• Carbon-carbon bond formation is crucial in organic synthesis.
• Palladium-PEPPSI complexes catalyze heteroarene arylation via C-H activation.
• Traditional heating methods for these reactions have environmental drawbacks, including high temperatures, catalyst loads, and reaction times.

Purpose of the Study:

• To develop new Pd-PEPPSI-NHC complexes for catalytic arylation.
• To investigate the efficiency of these catalysts under microwave irradiation.
• To provide a more environmentally friendly method for synthesizing biaryl scaffolds.

Main Methods:

• Synthesis of novel palladium-(II) complexes with N-heterocyclic carbene (NHC) ligands.
• Catalytic arylation of 2-acetylfuran and 2-acetylthiophene with aryl bromides.
• Application of microwave irradiation to accelerate the reaction.
• Characterization of the synthesized complexes using NMR (1H, 13C) and FT-IR spectroscopy.
• Structural elucidation of selected complexes (3b and 3e) via single-crystal X-ray diffraction.

Main Results:

• The new Pd-PEPPSI-NHC complexes effectively catalyzed the arylation of 2-acetylfuran and 2-acetylthiophene.
• The microwave-assisted protocol provided biaryl scaffolds in good yields.
• The catalytic loading was significantly reduced to 0.5 mol %.
• The reactions proceeded efficiently at 110 °C.
• The structures and square-planar geometry of the palladium complexes were confirmed.

Conclusions:

• Novel Pd-PEPPSI-NHC complexes are effective catalysts for C-H arylation.
• Microwave irradiation offers a faster and potentially greener approach compared to conventional heating.
• This method enables efficient synthesis of valuable biaryl scaffolds with reduced catalyst loading.