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Sensuke Ogoshi

Publications and source records attributed to Sensuke Ogoshi.

9 recordsLinked to original sources
PubMed2006

Reversible carbon-carbon bond formation between 1,3-dienes and aldehyde or ketone on nickel(0).

The reversible oxidative cyclization of dienes and aldehydes with nickel(0) proceeded to give eta(3):eta(1)-allylalkoxynickel complexes. The treatment of these complexes with carbon monoxide led to the formation of the corresponding lactone and/or the regeneration of a butadiene and an aldehyde concomitant with the formation of Ni(CO)(3)(PCy(3)). The scission of the nickel-oxygen bond of the allylalkoxy complexes with ZnMe(2) leading to eta(3)-allyl(methyl)nickel was very efficient to suppress the reverse reaction of the oxidative cyclization. The methylated eta(3)-allylnickel compound underwent the reductive elimination. The carbonylative coupling reaction of the eta(3)-allyl(methyl)nickel proceeded as well under a carbon monoxide atmosphere. Similarly, the addition of Me(3)SiCl to eta(3):eta(1)-allylalkoxynickel complexes was also efficient for the inhibition of the reverse reaction. The resulting eta(3)-1-siloxyethylallylnickel complex was treated with carbon monoxides followed by the addition of MeOH to give the expected hydroxyester. This method is efficient as well even for the eta(3):eta(1)-allyl(alkoxy)nickel complex containing acetone as a component, which was so prone to undergo the reverse reaction hampering its isolation. The isolation of the eta(3):eta(1)-allylalkoxynickel complex containing ketone as a component was made easier by the use of heavier butadiene and ketone, such as 2,3-dibenzyl-1,3-butadiene and benzophenone or by the use of cyclobutanone. The reaction with styrene oxide gave the eta(3):eta(1)-allylalkoxynickel containing phenylacetoaldehyde, an isomer of styrene oxide.

Journal Article↗
PubMed2003

New direction in organopalladium chemistry: structure and reactivity of unsaturated hydrocarbon ligands bound to multipalladium units.

Examination of the manner of interaction between Pd(0) and allylpalladium(II) complexes, both being involved as key intermediates in Pd-catalyzed allylic coupling, led us to discover a new role for such combinations in affecting the stereochemistry of the transformations. A similar investigation of the system involving Pd(0) and allenyl/propargyl complexes of Pd(II) led to the discovery of dinuclear Pd(I)bond;Pd(I) complexes containing bridging allenyl/propargyl ligands, which exhibited novel structural and reactivity aspects of great synthetic significance. A systematic comparison was made between the structure, stability, and reactivity of allyl and allenyl/propargyl ligands in dinuclear complexes and those in mononuclear counterparts. On the basis of MO calculations, coordination behavior specific to the ligands of the dinuclear complex is attributed to the occurrence of the back-donating interaction from filled Pdbond;Pd bonding orbitals to vacant ligand pi* orbitals. Similar bonding features are the origin of the ready synthesis of novel one-dimensional sandwich complexes composed of conjugated polyene ligands and linear polypalladium chains. A substitutionally labile dipalladium complex reacts with an equimolar amount of trienes or alkynes to give formal [4pi + 2sigma] or [2pi + 2sigma] adducts, respectively, which undergo further unique transformations with additional unsaturated substrates.

Journal Article↗