Polyvinylpyridine-Supported Palladium Nanoparticles: A Valuable Catalyst for the Synthesis of Alkynyl Ketones via Acyl Sonogashira Reactions

Palladium nanoparticles (NP) immobilized on metal scavengers (Smopex®-234, Smopex®-111, PVPy, 1% w/w) have been tested in the acyl Sonogashira reactions between terminal acetylenes and acid chlorides. Pd/PVPy resulted especially effective in the synthesis of alkynyl ketones with different stereoelectronic properties, even working with a very low amount of palladium (0.2 mol%). Preliminary tests seem to indicate that Pd/PVPy could act as a reservoir of very active palladium NP which are partially released during the reaction and then recaptured from the resin at the end of the process, thus ensuring the possibility of reuse of the catalyst.