Yusuke Oka

Showa University, Shinagawa, Tōkyō, Japan

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Publications (4)10.92 Total impact

  • Yuji Hanzawa · Yusuke Oka · Masaya Yabe
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    ABSTRACT: ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
    ChemInform 02/2008; 39(7). DOI:10.1002/chin.200807056
  • Yuji Hanzawa · Yusuke Oka · Masaya Yabe
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    ABSTRACT: Acylzirconocene chloride complex as an acyl group donor reacts with ω-carbonyl α,β-enones or with bis-enones to give carbocyclic compounds under 10mol% Pd(OAc)2-catalyzed conditions, and each reaction was accelerated by the addition of a stoichiometric amount of Me2Zn. The formation of the carbocycles from ω-carbonyl α,β-enones was considered to be a result of a series of reactions; (i) the formation of Pd(II)-intermediate by an electron transfer from the Pd(0)-catalyst to an α,β-enone function in an initial step, (ii) an acyl group transfer from the acylzirconocene complex to the Pd(II)-intermediate (transmetalation), (iii) the reductive elimination of Pd(0)-metal, and (iv) an intramolecular addition of metal enolate to ω-carbonyl group. On the other hand, the reaction of bis-enones with acylzirconocene chloride under the identical condition afforded reductive cyclization product, bicyclo[3.3.0] octane derivatives, in which acyl group from acylzirconocene complex was not incorporated.
    Journal of Organometallic Chemistry 10/2007; 692(21):4528-4534. DOI:10.1016/j.jorganchem.2007.04.033 · 2.17 Impact Factor
  • Akio Saito · Yusuke Oka · Yohei Nozawa · Yuji Hanzawa
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    ABSTRACT: NiCl2(PPh3)2-catalyzed reactions of 1,6-ynal or 1,6-enyne compounds with n-nonanoylzirconocene chloride afforded stereoselectively cyclopentane derivatives or bicyclo[3.1.0] compounds by catalytic cyclization/acylation reactions, which would involve (i) the primary formation of a metallacycle followed by (ii) the transfer of an acyl group from the acylzirconocene complex (transmetalation).
    Tetrahedron Letters 03/2006; 47(13):2201-2204. DOI:10.1002/chin.200627059 · 2.38 Impact Factor
  • Yuji Hanzawa · Masaya Yabe · Yusuke Oka · Takeo Taguchi
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    ABSTRACT: The acylzirconocene chloride complex as an acyl group donor reacts with omega-unsaturated alpha,beta-enones and -ynones under Pd-Me(2)Zn(Me(2)AlCl)-catalyzed conditions to give stereoselectively bicyclo[3.3.0] compounds through (i) formation of a Pd(II) intermediate by an oxidative addition of the Pd(0) catalyst to an enone function, (ii) cyclization of the Pd intermediate to an omega-unsaturated group, (iii) an acyl group transfer from zirconium to Pd metal, (iv) reductive elimination of the Pd metal, and (v) intramolecular cis-selective aldol reaction. [reaction: see text]
    Organic Letters 12/2002; 4(23):4061-4. DOI:10.1021/ol026770s · 6.36 Impact Factor