摘要：

This account describes development of new synthetic reactions utilizing palladium complexes bearing a PSiP-pincer type ligand as a catalyst. The PSiP-palladium complex was designed based on the expectations that 1) the strong trans influence and electron-donating nature of the silicon atom would enhance the reactivity of its trans substituent, 2) the rigid pincer structure based on the phenylene backbones would retard Pd(0) liberation and facilitate rational design of Pd (II)-based catalytic cycle, and 3) rather strained square planar structure of the PSiP-linkage would facilitate structural change to trigonal bipyramidal geometry, allowing facile coordination and activation of substrates. Consequently, we have developed hydrocarboxylation reaction of allenes and 1,3-dienes with CO2 and selective synthesis of monoboryl-and diborylalkenes via dehydrogenase borylation of alkenes with diboron. Both reactions are new type of molecular transformations and are realized by utilizing characteristics of the PSiP-palladium complexes. Furthermore, unique dynamic behaviors of the silicon atom were revealed through the reaction of ν2-(Si-H)Pd 0) complex, demonstrating promising utility of the PSiP-pincer ligand in organometallic and synthetic chemistry.

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