Palladium dichloride, benzonitrile complex

The formation of some silylated i73-allylic complexes has been, however, achieved by reacting substituted silyl olefins with bis(benzonitrile)palladium dichloride. The mechanism is rather complex and two olefin molecules are incorporated in the final i -allylic ligand 169) ... 

Several tr-allyl palladium chloride complexes have been prepared from steroidal olefins. Reaction of cholest-4-ene (65), for example, with bis(benzonitrile)palladium dichloride produced dimeric complexes of structures (66) and (67) (76). 

In a finding of greater practical significance. Overman and coworicers showed that the reactions could be carried out with catalytic amounts of the palladium(II) complex, and that the catalytic effect was broadly applicable to acyclic 1,5-dienes as well7 In a typical example (equation 32), 2-methyl-3-phe-nyl-l,5-hexadiene rearranges in 1 h at room temperature in 87% yield in the presence of 0.06 equiv. of bis(benzonitrile)palladium dichloride, in contrast to the thermal rearrangement which has t n = 13 h at 177 °C. The cat yst thus provides an estimated rate acceleration of about 10 °. The product is a 93 7 mixture of ( )- and (Z)-isomers, corresponding to the equilibrium ratio. Palladium acetate and tetra-kis(triphenylphosphine) were ineffective as catalysts. One serious limitation is that the catalyzed reaction occurs only with those 1,5-dienes which possess an alkyl or aryl substituent at C-2 or C-5 (but not both). 

Palladium salts, such as palladium dichloride and sodium tetrachloropalladate, also exhibit catalytic activity. Phosphane complexes, however, are completely inactive for this type of rearrangement. The stereochemical outcome of the bis(benzonitrile)dichloropa ladium(Il) catalyzed rearrangement of substrate 1 has been explained by a boatlike transition state where the diene moiety may act as a bidentate ligand344. The internal asymmetric induction is opposite to that in the 2,6-dimethylphenol catalyzed rearrangement (vide supra). 

Treatment of 4-vinylcyclohexene with bis-(benzonitrile)palladium dichloride gives the unrearranged rc,7i-complex of 4-vinylcyclohexene and not cyclo-octa-1,5-diene as reported earlier. 

Bis(benzonitrile)palladium dichloride reacts with the diazo-compoimd (CFaljCN, in methylene chloride to give complexes (156) and (157) in which insertion into the Pd—Cl bond has occurred." Insertion into the Pt—H bond occurs in the complex ra j-[(Et3P)2Pt(H)Cl] under more vigorous conditions, yielding cis- and tra -(Et3P)aPt[CH(CF3)2]Cl." ... 

Treatment of bis-benzonitrile palladium dichloride with allene affords a variety of w-enyl complexes depending on the stoicheiometry of the reaction, and on the solvent [24,25]. 

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