Main > ORGANIC CHEMICALS > Heck Reaction (See Dictionary) > Catalysts > Palladium. > Fluorinated Ligand Catalyst > Org.: USA. U (Fluorous Sepn. Tech.) > NPLS Contents

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One line of recent research MAIN AUTHOR highlighted at the symposium is palladium-catalyzed Heck coupling reactions. In one example, COAUTHORS synthesized a palladium catalyst with a cyclic fluorinated ligand that was used to couple iodobenzene with isoprene in tributylamine and dimethylacetamide. The reaction can be carried out conventionally at 140 °C to give the addition product in 95% yield, he noted. With microwave heating, the reaction takes place in 15 minutes, he said.

The product and catalyst were separated by MAIN AUTHOR s patented fluorous solid-phase extraction technique. This process relies on chromatography cartridges, which are packed with silica gel bonded with perfluoroalkyl chains, MAIN AUTHOR explained. In the case of the Heck reaction, the fluorinated catalyst is retained on the column and the nonfluorinated product is separated when flushed with a fluorophobic 90:10 methanol-water wash. The catalyst is then recovered by washing the column with pure methanol.

"This is an early example of catalyst recycling by solid-phase extraction,"MAIN AUTHOR said. "Before, the catalyst was only removed, but not recovered intact or was not good enough to be purified and reused." The speed of the coupling in the microwave reactions with fluorous solid-phase extraction is "a combination that is prized in discovery settings, such as parallel synthesis," he added



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