Fast Suzuki–Miyaura cross-coupling reaction catalyzed by the Na2Pd2Cl6 complex with ethyl calix[4]aryl acetate at room temperature in aqueous medium under ligand-free and ambient atmosphere

The new Na2Pd2Cl6 complex with ethyl calix[4]aryl acetate 2 was prepared simply and efficiently by the extraction of sodium ion from Na2PdCl4 aqueous solution with ethyl calix[4]aryl acetate. The structure of complex 2 could be verified by X-ray single crystal structure determination. The complex 2 was tested as catalyst in Suzuki–Miyaura cross-coupling reaction at room temperature in CH3OH/H2O medium under ambient conditions. Using 0.2 mol% of the complex 2 in the presence of K2CO3 as base offered excellent yields in the reaction of activated and non-activated aryl bromides with aryl boronic acids within 10 min. The key for achieving a very rapid and almost quantitative coupling is probably the use of ethyl calix[4]aryl acetate possessing extended hydrophobic host cavities and surface active properties. In addition, it was found that both solvent and base had a fundamental influence on the reaction.

A convenient and efficient methodology for the Suzuki–Miyaura cross-coupling reaction of aryl bromides and aryl boronic acids catalyzed by the Na2Pd2Cl6 complex with ethyl calix[4]aryl acetate at room temperature in aqueous medium under ligand-free and ambient conditions with the low catalyst loadings (0.2 mol%) have been developed.Figure optionsDownload as PowerPoint slideHighlights
► The Na2Pd2Cl6 complex with ethyl calix[4]aryl acetate as catalysts.
► The room temperature Suzuki–Miyaura cross-coupling reaction in aqueous medium with the low catalyst loadings.
► The reaction time is 10 min in the absence of any conventional ligand.