• Title/Summary/Keyword: Alkenes

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Thexylalkoxyborane as Hydroborating Agent for Alkenes and Alkynes

  • 차진순;서원우;김종미;권오운
    • Bulletin of the Korean Chemical Society
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    • v.17 no.10
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    • pp.892-899
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    • 1996
  • In order to elucidate the effect of alkoxy substituent in thexylborane and hence establish their usefulness as hydroborating agent, reactions of alkenes and alkynes with thexylalkoxyborane (ThxBHOR; R=Et, i-Pr, i-Bu, sec-Bu, t-Bu, Ph) were investigated in detail. The reagents readily hydroborated alkenes and alkynes of various structural types at 25 ℃ in excellent regioselectivity. The selectivity increases consistently with increasing steric size of alkoxy substituent. Especially, the selectivity achieved by the sec-butoxy derivative is comparable to that previously achieved by thexylhaloborane-methyl sulfide (ThxBHX·SMe2), the most selective hydroborating agent known.

Ruthenium Complex-catalyzed Highly Selective Co-oligomerization of Alkenes

  • Ura, Yasuyuki;Tsujita, Hiroshi;Mitsudo, Take-Aki;Kondo, Teruyuki
    • Bulletin of the Korean Chemical Society
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    • v.28 no.12
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    • pp.2139-2152
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    • 2007
  • Ruthenium complex-catalyzed reactions often require highly qualified tuning of reaction conditions with substrates to attain high yield and selectivity of the products. In this review, our strategies for achieving characteristic ruthenium complex-catalyzed co-oligomerization of different alkenes are disclosed: 1) The codimerization of 2-norbornenes with acrylic compounds by new ruthenium catalyst systems of RuCl3(tpy)/Zn [tpy = 2,2':6',2''-terpyridine] or [RuCl2(η6-C6H6)]2/Zn in alcohols, 2) A novel synthesis of 2-alkylidenetetrahydrofurans from dihydrofurans and acrylates by zerovalent ruthenium catalysts, such as Ru(η4-cod)(η6-cot) [cod = 1,5-cyclooctadiene, cot = 1,3,5-cyclooctatriene] and Ru(η6-cot)(η2-dmfm)2 [dmfm = dimethyl fumarate], 3) Regio- and stereoselective synthesis of enamides by Ru(η6-cot)(η2-dmfm)2-catalyzed codimerization of N-vinylamides with alkenes, and 4) Unusual head-to-head dimerization of styrenes and linear codimerization of styrenes with ethylene by Ru(η6-cot)(η2-dmfm)2 catalyst in the presence of primary alcohols.

Platinum/Nickel Catalyzed Selective Hydrosilylation of Alkynes and Alkenes with 1,1'-Bis(dimethylhydrosilyl) Ferrocene (백금/니켈 촉매를 이용한 1,1'-Bis(dimethylhydrosilyl)ferrocene과 Alkynes, Alkenes의 선택적 Hydrosilyation 반응)

  • Kim, Jin-Sik;Kong, Young-Kun
    • Journal of the Korean Chemical Society
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    • v.54 no.1
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    • pp.27-37
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    • 2010
  • The reaction of 1,1'-bis(dimethylhydrosilyl)ferrocene with alkynes in the presence of a catalytic amount of ($C_2H_4$)Pt$(PPh_3)_2$ leads to the acyclic mixture of monohydrosilylated and/or dihydrosilylated compounds. But the analogous reactions in the presence of Ni$(PEt_3)_4$ catalyst yield monohydrosilylated compounds or dihydrosilylated products. The monohydrosilylated products were generated from the reactions of alkenes with the silylated ferrocene using nickel catalyst.

Epoxidation of Simple Alkenes with O2 and Isobutyraldehyde Catalyzed by Ni Catalysts Deposited on Nanoporous Carbon

  • Lim, So-Young;Kang, Min;Kim, Ji-Man;Lee, Ik-Mo
    • Bulletin of the Korean Chemical Society
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    • v.26 no.6
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    • pp.887-891
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    • 2005
  • Novel nickel catalyst deposited on nanoporous carbon was found to be an efficient catalyst for the epoxidation of simple alkenes with $O_2$ and isobutyraldehyde under mild conditions. Alkenes exhibited different reactivities towards Ni-catalyst and epoxidation with stilbene proceeds stereospecifically. This may be rationalized with the mechanism involving coordinated acylperoxy radical intermediate. Nickel contents depend on the preparative methods and the KNI-3 catalyst, which was synthesized by wet impregnation of $Ni(NO_3)_2$ into nanoporous carbon, shows the highest activity. The activity of the catalyst is well correlated with contents of nickel. Recycled catalysts suffer considerable loss of activity due to leaching of catalytic active species, nickel.

Addition of α,α-Difluoroiodomethyl Ketones to Alkenes with a Copper Catalyst

  • Kwak, Kyung-Chell;Lee, Woo-Yiel;Zheshan, Quan;Lee, Young-Hang;Yun, Young-Gab;Kwak, Gyu-Beum;Chung, Hun-Taeg;Kwon, Tae-Oh;Chai, Kyu-Yun
    • Bulletin of the Korean Chemical Society
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    • v.26 no.1
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    • pp.97-102
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    • 2005
  • The addition reactions of $\alpha$,$\alpha$-difluoroiodomethyl n-butyl ketone, α,α-difluoroiodomethyl cyclohexyl ketone, or $\alpha$,$\alpha$-difluoroiodomethyl phenyl ketone to alkenes were successfully accomplished in good yields in the presence of copper powder. The reaction was also applicable to alkenes containing a variety of functional groups such as ester, trimethylsilyl, or ether group. Acetonitrile was determined to be the best solvent in the present study and the reaction was performed at 55 ${^{\circ}C}$ for 15-22 h. This reaction provides a new, efficient and general method for the synthesis of $\alpha$,$\alpha$-difluoro functionalized ketones.