Advantages • Green Reaction Medium: The use of glycerol as a biodegradable, nonvolatile, and low-toxicity solvent makes the protocol environmentally friendly and aligns well with green chemistry principles. • Magnetically Recoverable Catalyst: The MWCNTs/MNPs-MT-Pd(0) nanocatalyst can be easily separated from the reaction mixture using an external magnet, enabling rapid and clean catalyst recovery. • High Catalytic Efficiency: Excellent yields (up to 98%) are achieved within short reaction times (3 h), reflecting high turnover numbers and efficient utilization of palladium. • Broad Substrate Scope: A wide variety of aryl and alkyl iodides and terminal alkynes, including heteroaryl and sterically demanding substrates, are well tolerated under the optimized conditions. • Excellent Recyclability and Stability: The catalyst maintains high activity over at least eight consecutive reaction cycles with minimal loss of performance and no significant structural degradation. • Operational Simplicity and Safety: The method employs mild base (KOAc), avoids toxic amine bases and acid chlorides, and uses Mo(CO)₆ as a convenient in situ CO source, making the procedure safer and easier to handle. • High Structural Stability of the Catalyst: Extensive postreaction analyses (FT-IR, XRD, SEM, TEM, and VSM) confirm that the nanocatalyst retains its structural integrity, crystallinity, and magnetic properties after multiple catalytic cycles, indicating strong metal–support interactions and resistance to Pd leaching or aggregation. • High Functional Group Tolerance: The catalytic system efficiently accommodates electron-donating and electron-withdrawing substituents, heteroaryl groups, and sterically hindered substrates without significant loss of activity, demonstrating its versatility and applicability to the synthesis of structurally diverse ynones. A magnetically recoverable palladium nanocatalyst supported on multi-walled carbon nanotubes and magnetic nanoparticles (MWCNTs/MNPs-MT-Pd(0)) has been developed and successfully applied to the carbonylative Sonogashira coupling for the efficient synthesis of ynones. The multifunctional nanocomposite was prepared through stepwise surface functionalization of MWCNTs with Fe₃O₄ nanoparticles and a melamine–thiourea ligand, followed by immobilization and in situ reduction of Pd(II) to Pd(0). Comprehensive characterization by FT-IR, BET, TGA, XRD, VSM, SEM, TEM, EDX, and ICP-OES confirmed the successful construction, high dispersion of Pd(0), and excellent thermal and magnetic properties of the catalyst. Under optimized conditions using glycerol as a green solvent, KOAc as a mild base, and Mo(CO)₆ as an in-situ CO source, a wide range of aryl and alkyl iodides and terminal alkynes were converted to the corresponding ynones in high to excellent yields (80–98%) within short reaction times. The heterogeneous catalyst exhibited outstanding recyclability, maintaining high activity over eight consecutive cycles without significant structural degradation. This sustainable, copper-free protocol combines high efficiency, broad substrate scope, and easy catalyst recovery, offering a practical green alternative for carbonylative ynone synthesis.
Shuheil et al. (Sun,) studied this question.