134029-36-0Relevant academic research and scientific papers
Reactions of electron-rich arylpalladium complexes with olefins. Origin of the chelate effect in vinylation catalysis
Portnoy,Ben-David,Rousso,Milstein
, p. 3465 - 3479 (2008/10/08)
Reaction of (dippp)Pd(Ph)Cl (1) with norbornene or styrene yields (dippp)PdCl2 (8) and (dippp)Pd(η2-olefin). Kinetic follow-up reveals fast formation of (dippp)Pd(phenylnorbornyl)-Cl (10), followed by its slow decomposition, with ks
A binuclear palladium(I) hydride. Formation, reactions, and catalysis
Portnoy, Moshe,Milstein, David
, p. 600 - 609 (2008/10/08)
(dippp)Pd(Ph)Cl (3) reacts with methanol to yield the novel hydrido Pd(I) dimer {[(dippp)-Pd]2(μ-H)(μ-CO)}+Cl- (1), (dippp)PdCl2 (4), H2, benzene, and formaldehyde. In the presence of NEt3, HNEt3+Cl- is formed instead of 4. 1 can also be formed in a reaction of Pd(dippp)2, HCl, and CO. Labeling studies and modeling reactions indicate that the novel transformation of 3 into 1 involves methanolysis of 3 followed by a β-H elimination from a methoxo intermediate to yield formaldehyde, benzene, and the 14e transient (dippp)Pd (7). Formaldehyde decarbonylation, coupling of the palladium carbonyl complex with 7, and protonation lead to 1. Alternatively, 1 can be formed by electrophilic attack of protonated 7, on the carbonyl complex (dippp)Pd(CO). A number of reactivity modes have been identified for 1. Reaction with acetylenes results in bridge-splitting to form (dippp)Pd(η2-acetylene) and in hydropalladation of the acetylene to form a vinyl complex. The hydropalladation process exhibits high regio- and stereoselectivity, resulting in cis addition and attachment of the Pd atom to the more hindered carbon, indicating electronic control. 1 undergoes exchange of the hydride for deuteride in CD3COCD3, most likely via an enol insertion into Pd-H. In the presence of an olefin, such as cyclooctene or ethyl vinyl ether, catalytic transfer deuteration takes place. α-Deuteration of the latter is preferred, indicating anti-Markovnikov Pd-H addition. The integrity of 1 is maintained during this process. With norbornene, bridge-splitting to form (dippp)Pd(norbornyl) (17) and its CO-insertion product 18 takes place. No H/D exchange catalysis is observed in this case with acetone-d6. 1 behaves as a Pd(O) complex and exhibits oxidative addition reactivity with chlorobenzene or benzyl chloride, yielding (dippp)Pd(R)Cl. The relevance of this reactivity to Pd-catalyzed reactions is discussed.
