Copper-free monomeric and dendritic palladium catalysts for the Sonogashira reaction: substituent effects, synthetic applications, and the recovery and re-use of the catalysts.
A series of bis(tert-butylphosphine)- and bis(cyclohexylphosphine)-functionalized Pd(II) monomers and polyamino (DAB) dendritic catalysts were synthesized and investigated for Sonogashira carbon-carbon coupling reactions in a copper-free procedure. The influence of phosphine substituents (tBu versus Cy) on the reaction kinetics was investigated by a GPC technique to monitor the reactions. The dendritic catalysts containing the cyclohexylphosphine ligands could be recovered and reused without loss of efficiency until the fifth cycle. The dendritic Pd(II) catalysts show a negative dendritic effect, that is, the catalyst efficiency decreases as the dendrimer generation increases.
Heuzé
Karine
K
Nanosciences and Catalysis Group, LCOO, UMR CNRS No. 5802 University Bordeaux I, 351 cours de la Libération, 33405 Talence, France. k.heuze@lcoo.u-bordeaux1.fr
Méry
Denise
D
Gauss
Dominique
D
Blais
Jean-Claude
JC
Astruc
Didier
D
D002384:Catalysis; D007700:Kinetics; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry; D010165:Palladium / Q000737:chemistry*
D009942:Organometallic Compounds; D010165:Palladium