2005 Fiscal Year Final Research Report Summary
Bond Formation in Tight Coordination Sphere on Small Transition metal
| Project/Area Number |
16550096
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Synthetic chemistry
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| Research Institution | Osaka University |
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Principal Investigator |
OGOSHI Sensuke Osaka University, Graduate School of Engineering, Associate Professor, 大学院・工学研究科, 助教授 (30252589)
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| Project Period (FY) |
2004 – 2005
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| Keywords | nickel / oxidative cyclization / carbonyl / alkene / butadiene / organoaluminum |
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| Research Abstract |
The addition of 1,5-hexenal or o-allylbenzaldehyde to a solution of Ni(cod)_2 and PR_3 (PCy_3 or PPh_3,1 equiv) gave η^2-alkene:η^2-aldehyde complexes quantitatively. Heating the solution at 60℃ or 80℃ resulted in the oxidative cyclization to give nickelacycle complexes. The direct observation of oxidative cyclization from η^2-carbonyl:η^2-olefin coordination complex to five membered metalacycle has not been reported even with early transition metal systems. AlMe_3 promoted the oxidative cyclization of η^2:η^2-2-allylacetophenone- or η^2:η^2-2-allylbenzophenone nickel complex to give an intriguing nickel-aluminum dinuclear complex. The molecular structure was determined by X-ray diffraction analysis. This complex is a nice model as an intermediate in the transmetallation process. Moreover, the cycloisomerization can proceed catalytically in THF.
The reversible oxidative cyclization of dienes and aldehydes with nickel(0) proceeded to give η^3:η^1-allylalkoxynickel complexes. The treatmen
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t 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 nickel-oxygen bond of the allylalkoxy complexes with ZnMe_2 leading to η^3-allyl(methyl)nickel was very efficient to suppress the reverse reaction of the oxidative cyclization. The methylated η^3-allylnickel compound underwent the reductive elimination. The carbonylative coupling reaction of the η^3-allyl(methyl)nickel proceeded as well under a carbon monoxide atmosphere. Similarly, the addition of Me_3SiCl to η^3:η^1-allylalkoxynickel complexes was also efficient for the inhibition of the reverse reaction. The resulting η^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 η^3:η^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 η^3:η^1-qllylalkoxynickel complex containing ketone as a component was made easier by the use of heavier butadiene and ketone, such as 2,3-dibenzyl-1,3-butadine and benzophenone or by the use of cyclobutanone. The reaction with styrene oxide gave the η^3:η^1-allylalkoxynickel containing phenylacetoaldehyde, an isomer of styrene oxide. Less
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