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Pd–Tetrahydrosalan‐Type Complexes as Catalysts for Sonogashira Couplings in Water: Efficient Greening of the Procedure
Author(s) -
Voronova Krisztina,
Homolya Levente,
Udvardy Antal,
Bényei Attila C.,
Joó Ferenc
Publication year - 2014
Publication title -
chemsuschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.412
H-Index - 157
eISSN - 1864-564X
pISSN - 1864-5631
DOI - 10.1002/cssc.201402147
Subject(s) - sonogashira coupling , catalysis , aryl , yield (engineering) , chemistry , aqueous solution , palladium , halide , aqueous medium , filtration (mathematics) , coupling reaction , inorganic chemistry , combinatorial chemistry , organic chemistry , materials science , alkyl , mathematics , metallurgy , statistics
New sulfonated tetrahydrosalen‐type ligands and their water‐soluble palladium(II) complexes have been synthesized. The palladium(II) complexes catalyze the Sonogashira coupling (23 examples) of various aryl halides (including chloroarenes) with terminal alkynes, with good to excellent conversions under mild conditions (80 °C, air, no Cu I cocatalyst) in aqueous–organic mixtures and turnover frequencies of up to 2790 h −1 . Under optimized reaction conditions to minimize environmental contamination, diphenylacetylenes can be isolated in 76–98 % yield. The aqueous catalyst solution can be recycled four times with decreasing activity; however, yields between 93 and 98 % can still be achieved with extended reaction times. Several water‐insoluble products can be isolated in excellent yield by simple filtration and purification by washing with water; this method is used, for the first time, for this type of CC coupling procedure.