![Mizoroki-Heck Cross-coupling Reactions Catalyzed by Dichloro{bis[1,1',1''-phosphinetriyltripiperidine]}palladium Under Mild Reaction Conditions](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F51444.jpg&w=3840&q=50)
The role of the stabilizing/leaving group in palladium catalysed cross-coupling reactions
Lorenzo Palio1,2, Francis Bru1, Tommaso Ruggiero1
1Department of Chemistry, Center for Sustainable Chemistry, Ghent University, Krijgslaan 281 (S-3), 9000, Ghent, Belgium.
Abstract:
Despite the widespread use of well-defined PdII complexes as pre-catalysts for cross-coupling processes, the role of the throw-away ligand is still underexplored. In this work we focused on the complexes of the type [Pd(NHC)(η3-R-allyl)Cl] (NHC = N-heterocyclic carbene) and we investigated the influence of the R substitution on the allyl moiety. Starting from the already described [Pd(IPr)(η3-cinnamyl)Cl] and [Pd(IPr*)(η3-cinnamyl)Cl] (IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene, IPr* = N,N'-1,3-bis[2,6-bis(diphenylmethyl)-4-methylphenyl]imidazol-2-ylidene) we prepared eight new complexes bearing new substitutions on the cinnamyl motif and we tested them in the C-N bond formation to evaluate the effect of the throw-away ligand modification in the catalytic activity. In addition, we studied the undesired formation of the less active off-cycle [PdI2(NHC)2(η3-R-allyl)(μ-Cl)] dimers from the corresponding PdII complexes to evaluate the role of the new throw-away ligands on the inhibition of this process.
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