• Title/Summary/Keyword: Benzylic

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Regioselective Benzylic Thioether Formation from Polybydroxy Stilbene

  • Koh, Dongsoo;Park, Jongmin;Lim, Yoongho
    • Journal of Applied Biological Chemistry
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    • v.44 no.1
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    • pp.20-22
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    • 2001
  • We have attempted to synthesize polyhydroxy stilbene compounds through the benzyl thioether moiety. During synthesis, we unexpectedly observed that demethylation of the compound under $AlCl_3$ in ethanethiol resulted in a regioselective addition of thiol to the double bond as well as complete demethylation. We report on the regioselective short synthesis for general structure and its structural identification.

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New Crown Compounds Derived from 1,2-Bis(2-hydroxybenzyl)benzene(I)

  • Woo Young Lee;Chang HePark e;Sung-Hwan Bang;Lee Sang Goo;Sim Won Bo
    • Bulletin of the Korean Chemical Society
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    • v.10 no.6
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    • pp.521-524
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    • 1989
  • By cyclocondensation of 1,2-bis(2-hydroxybenzyl)benzene with oligoethylene glycol ditosylate, new crown ethers containing 1,2-dibenzylbenzene subunit were synthesized. By oxidation of the benzylic positions of them, carbonyl-containing crowns having 1,2-dibenzoylbenzene subunit were synthesized.

Catalytic Hydrogenation of Aromatic Nitro Compounds over Borohydride Exchange Resin Supported Pd (BER-Pd) Catalyst

  • Yoon, Nung-Min;Lee, Hyang-Won;Choi, Jae-Sung;Lee, Hyun-Ju
    • Bulletin of the Korean Chemical Society
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    • v.14 no.2
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    • pp.281-283
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    • 1993
  • Aromatic nitro compounds are selectively hydrogenated to the corresponding amines in high yields at room temperature and atmospheric pressure using BER-Pd catalyst without affecting ketone, ether, ester, nitrile or chloro groups also present. Especially the nitro group in 4-nitrobenzyl alcohol, methyl 4-nitrobenzyl ether and N-N-dimethyl 4-nitrobenzylamine is selectively hydrogenated with this catalyst to give the corresponding amines without hydrogenolysis of benzylic groups. And aromatic nitro compound can be reduced selectively in the presence of aliphatic nitro compound.

1-(p-Substituted)benzyl-1,1-dimethyl-2-(p-substituted)benzoyl Hydrazinium Hexafluoroantimonates as Useful Catalysts for the Acetalization of Carbonyl Compounds with Diols

  • 이상봉;정혜인;이규완
    • Bulletin of the Korean Chemical Society
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    • v.17 no.4
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    • pp.362-365
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    • 1996
  • Carbonyl compounds 1, alkyl- and arylaldehydes and alkyl, aryl, benzylic, and cyclic ketones were converted to the corresponding 1,3-dioxolanes 2 and 1,3-dioxanes 4 with ethylene glycol and 2,2-dimethyl-1,3-propanediol in the presence of 1-3 mol% of 1-(p-substituted)benzyl-1,1-dimethyl-2-(p-substituted)-benzoyl hydrazinium hexafluoroantimonates 3 in high yields.

Identification of the chromophoric structure in alkali model lignin by 13C-NMR (13C-NMR에 의(依)한 알카리 모델리그닌의 착색구조(着色構造)에 관(關)한 연구(硏究))

  • Yoon, Byung Ho
    • Journal of Korean Society of Forest Science
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    • v.43 no.1
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    • pp.14-19
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    • 1979
  • On treatment with sodium hydroxide at $165^{\circ}$ for 1.5~3hr followed by air oxidation. vanillyl alcohol afforded colored materials. $^{13}C$-NMR spectrum of the material did not show any absorptions assigned to the carbons of chromophoric structures, but gave the valuable information on the chemical structures of the condensation products. On the other hand, the colored material specifically labelled by $^{13}C$ at the benzylic position was prepared by alkali treatment of vanillyl alcohol-[carbinol-$^{13}C$] followed by air oxidation, and $^{13}C$-NMR spectra of the material exhibited absorptions at 101.7 and 104.6 ppm due to the carbons of a quinonemethide structure, indicating that the quinomethide unit would be one of the important types of chromophores in which benzylic carbon of vanillyl alcohol was included.

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An Efficient and Mild Oxidation of α-Isophorone to Ketoisophorone Catalyzed by N-Hydroxyphthalimide and Copper Chloride

  • Chen, Lihua;Tang, Ruiren;Li, Zhongying;Liang, Shan
    • Bulletin of the Korean Chemical Society
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    • v.33 no.2
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    • pp.459-463
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    • 2012
  • N-hydroxyphthalimide (NHPI) and copper chloride ($CuCl_2$) were first utilized for aerobic oxidation of ${\alpha}$-isophorone (${\alpha}$-IP) to ketoisophorone (KIP) and the effects of co-catalysts, temperature, reaction time, solvent, amount of $CuCl_2$ and pressure of oxygen were investigated extensively. NHPI/$CuCl_2$ turned out to be highly efficient to this oxidation with up to 91.3% conversion and 81.0% selectivity under mild conditions. And various hydrocarbons including benzylic compounds, cycloalkene and its derivatives were also oxidized smoothly under optimized conditions. Moreover, the possible reaction mechanism was proposed and verified by FT-IR spectra.

Enantioselective Hydrosilylation of Imines Catalyzed by Diamine-Zinc Complexes

  • Park, Bu-Mahn;Feng, Xinhui;Yun, Jae-Sook
    • Bulletin of the Korean Chemical Society
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    • v.32 no.spc8
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    • pp.2960-2964
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    • 2011
  • The efficient asymmetric hydrosilylation of imines in the presence of polymethylhydrosiloxane has been investigated by screening chiral diamine-zinc complexes. A series of chiral diamine ligands were prepared from optically pure 1,2-diphenyl-1,2-ethanediamine and screened for effectiveness. N-Benzylic substituents were required for high enantioselectivity; ligands with bulky groups or extra coordinating groups such as OH and S lowered the catalytic activity. The level of asymmetric induction was usually in >90% ee range for aromatic imine substrates. A linear correlation between the ee of the ligand and that of the product was observed, indicating the presence of a 1:1 ratio of ligand to metal coordination in the active catalytic complex.