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Sulfonated N ‐Heterocyclic Carbenes for Pd‐Catalyzed Sonogashira and Suzuki–Miyaura Coupling in Aqueous Solvents
Author(s) -
Roy Sutapa,
Plenio Herbert
Publication year - 2010
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.200900886
Subject(s) - sonogashira coupling , chemistry , catalysis , aryl , aqueous solution , palladium , carbene , salt (chemistry) , coupling reaction , organic chemistry , isopropyl alcohol , polymer chemistry , alkyl
Abstract The reactions of the N,N′ ‐diarylimidazolium and N,N′ ‐diarylimidazolinium salts with chlorosulfonic acid result in the formation of the respective disulfonated N ‐heterocyclic carbene (NHC) precursors in reasonable yields (46–77%). Water‐soluble palladium catalyst complexes, in situ obtained from the respective sulfonated imidazolinium salt, sodium tetrachloropalladate (Na 2 PdCl 4 ) and potassium hydroxide (KOH) in water, were successfully applied in the copper‐free Sonogashira coupling reaction in isopropyl alcohol/water mixtures using 0.2 mol% catalyst loading. The preformed (disulfonatedNHC)PdCl(cinnamyl) complex was used in aqueous Suzuki–Miyaura reactions at 0.1 mol% catalyst loading. The coupling protocol reported here is very useful for Sonogashira reactions of N ‐ and S ‐heterocyclic aryl bromides and chlorides with aryl‐ and alkylacetylenes.