Development of Palladium-Catalyzed Transformations Involving ?1-Allypalladium Species

Abstract: This thesis is focused on investigation of the structure, reactivity and isomerization reactions of ?1-allylpalladium complexes, which are key intermediates in catalytic transformations. The first part of this thesis concerns the structure and reactivity of bis-allylpalladium complexes. We have studied the regioselective palladium-catalyzed coupling reaction of various dialkylsubstituted allyl chlorides with allylstannanes and benzylidenemalonitrile, affording functionalized 1,7-octadienes. We have also found that benzylidenemalonitrile can be replaced by isocyanates providing bis-allylated amides. The second part is a computational study on the ?3-?1-?3 isomerization of allylpalladium complexes. The mechanism of the isomerization was studied by DFT. It was found that the isomerization involves tetra-coordinated ?1-allylpalladium intermediates. Alkyl substitution of the metalated carbon leads to destabilization of the ?1-allylpalladium intermediate, which increases the activation energy of the isomerization process. The last part describes our efforts to extend the synthetic scope of mono-allylpalladium chemistry to include catalytic allylation of imine and aldehyde substrates. We have found that this reactivity can be achieved by the use of strongly coordinating tridentate ligands on palladium. The ?1-allylpalladium intermediate has been observed by NMR-spectroscopy, and DFT calculations have been performed to show the feasibility of an electrophilic attack occuring on the allyl moiety.