A novel binucleating ligand,
N,
N'-bis [2-(diphenylphosphino) phenyl] formamidine (Hdpfam) has been prepared and utilized for the synthesis of dinuclear palladium complexes Pd
2R
2 (μ-X) (μ-dpfam) (R=Ar, Me, X=Cl, Br, I, OH).Hydroxo-bridged complexes Pd
2R
2 (μ-OH) (μ-dpfam) served as catalyst for the
cis-addition of aromatic C-H bonds to alkynes in the presence of catalytic amounts of tri-
n-butylborane. In contrast to the Friedel-Crafts type reaction, electron-poor arenes also can be used for the addition reaction. In the reaction of monosubstituted arenes, meta isomers were main products in all cases. The addition of olefinic C-H bonds of indene to alkynes was also achieved by using chloro-bridged complexes Pd
2R
2 (μ-Cl) (μ-dpfam) and LiAlH (OBu
t)
3 as catalyst. The palladium complexes supported by dpfam catalyzed the cross-addition of triisopropylsilylacetylene to various internal and terminal unactivated alkynes, giving enynes in high yields.
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