A rhodium(III)-catalyzed Satoh−Miura type oxidative annulation of N-aryl 2-pyridone derivatives is described using internal alkyne as a coupling partner. A weakly coordinating carbonyl group of the 2-pyridone ring is utilized for this transformation. The reaction proceeds with a broad scope and wide functional group tolerance. The solvent plays an important role in the developed method to furnish a different class of annulated product. A preliminary investigation was carried out to explore the photophysical properties of the obtained polyarylated N-naphthyl 2-pyridones.A mong various known 2-pyridone-based moieties, the Naryl 2-pyridone scaffold is considered as an important structural scaffold due to its frequent presence in pharmaceuticals, drug molecules, and organic materials (Figure 1). 1
A Pd(II)-catalyzed straightforward oxidative naphthylation of unmasked 2-pyridone derivatives is described using a twofold internal alkyne as a coupling partner. The reaction proceeds through N−H/C−H activation to provide polyarylated Nnaphthyl 2-pyridones. An unusual oxidative annulation at the arene C−H bond of the diarylalkyne leads to the formation of polyarylated N-naphthyl 2-pyridones, where the 2-pyridone-attached phenyl ring of the naphthyl ring is polyaryl-substituted. Mechanistic studies and DFT calculations suggest a plausible mechanism based on N−H/C−H activation. The N-naphthyl 2pyridone derivatives were studied to explore encouraging photophysical properties.
It is essential to replace the conventional toluene chlorination process to produce industrially important benzaldehyde with a more ecofriendly process. In that direction, we have developed polymer-conjugated magnetic nanoparticles as "green catalysts". Poly[(N-isopropylacrylamide-b-acrylic acid)] and poly-[(N-isopropylacrylamide-r-N-vinylpyrrolidone)-b-(acrylic acid)] coated magnetic nanoparticles showed high catalytic activity in the synthesis of benzaldehyde by styrene oxidation reaction at room temperature in water using hydrogen peroxide as an oxidizer. The presence of hydrophilic polymers on nanoparticle surfaces improved the aqueous dispersibility, enabling quasi-homogeneous catalysis in water at room temperature. The conversion of styrene to benzaldehyde and styrene oxide can be regulated by varying the temperature, owing to the temperature responsiveness of the block copolymers. Parameters like catalyst concentration, temperature, and time were varied to achieve an optimal reaction condition. The catalysts can be quickly recovered using their magnetic property and reused without noticeable loss in catalytic activity. Thus, these two nanoparticle systems showed great potential for green nanocatalysts in industrial use.
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