Novel ultra-small Pd NPs on SOS spheres: a new catalyst for domino intramolecular Heck and intermolecular Sonogashira couplings

• Published in: RSC advances Vol. 10; no. 8; pp. 4568 - 4578
• Main Authors: Lakshminarayana, Bhairi, Vinodkumar, T, Satyanarayana, G, Subrahmanyam, Ch
• Format: Journal Article
• Language: English
• Published: England Royal Society of Chemistry 28.01.2020; The Royal Society of Chemistry
• Subjects: Alkynes; Catalysts; Chemistry; Couplings; Covalent bonds; Nanoparticles; Palladium; Silica fume; Silicon dioxide; X ray photoelectron spectroscopy
• ISSN: 2046-2069; 2046-2069
• DOI: 10.1039/c9ra09429f

We report a novel catalyst Pd/SOS that catalyzes the dual C-C bond forming coupling of an iodoarene moiety with an internal alkene and an external alkyne an intramolecular Heck reaction, followed by an intermolecular Sonogashira reaction, respectively. The catalyst was characterized using XRD, IR, XPS, SEM and TEM analyses. Notably, for the first time, cheap and readily available new silica [nanosilica on microsilica (SOS)] material-supported ultra-small Pd nanoparticles (2.20 nm) are employed for the efficient synthesis of dihydrobenzofuran and oxindole derivatives in a domino one-pot reaction. Significantly, a sub-molar quantity of Pd (0.3 mol%) was found to be sufficient to furnish the products in very good to near quantitative yields. Gratifyingly, the catalyst could be recycled up to five cycles with a marginal loss (∼no loss) of the product.