• 제목/요약/키워드: o-alkylation

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Theoretical Studies on the Gas-Phase Alkylation of Delocalized Ambident Anions with Methyl Fluoride

  • 이익춘;박형연;한인숙;김창곤;김찬경;이본수
    • Bulletin of the Korean Chemical Society
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    • 제20권5호
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    • pp.559-566
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    • 1999

  • Gas-phase alkylations of delocalized ambident anions, Y---CH---X- where X, Y=CH2, O, or S, have been investigated theoretically at the MP2/6-31+G*//MP2/6-31+G* and QCISD/6-31+G*//MP2/6-31+G* lev-els. O-and S-alkylations (X=O and S) are more favored kinetically by ΔE^≠ = 4.6 and 9.8 kcal mol-1 than the respective C-alkylations even though they are thermodynamically less favored by 22.4 and 6.0 kcal mol-1 respectively. It was found that the transition structures for the C-alkylations are imbalanced due to the endoergic rehybridi-zation of the carbon center from sp2 to sp3 which leads to premature bond contraction of the C-Y bond and delayed bond stretching of the C-X bond. In the O-, or S-alkylation, such endoergic process is not required since the σ-lone pair on O or S is involved in the initial stage of alkylation. The imbalanced TSs for the C-alkylation are accompanied by higher intrinsic barriers and deformation energies.

  • https://doi.org/10.5012/bkcs.1999.20.5.559 인용 PDF

헤테로폴리산 촉매상에서 1-부텐에 의한 i-부탄의 알킬화반응 (Alkylation of Isobutane with 1-Butene over Heteropoly Acid Catalysts)

  • 홍성희;이화영;송인규
    • 공업화학
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    • 제8권2호
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    • pp.211-219
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    • 1997

  • 1-부텐과 i-부탄의 알킬화반응에 의한 i-옥탄 생성반응을 Cs 혹은 $NH_4$가 치환된 $H_3PW_{12}O_{40}$ 촉매상에서 액상 및 기상으로 수행하였다. 액상알킬화반응의 경우 반응전 촉매의 전처리 온도가 헤테로폴리산 촉매의 반응성에 매우 중요한 역할을 하였다. 액상알킬화반응에서 치환염은 모산보다 매우 우수한 총수율과 i-옥탄 선택도를 보였으며, $(NH_4)_{2.5}H_{0.5}PW_{12}O_{40}$ 촉매는 $Cs_{2.5}H_{0.5}PW_{12}O_{40}$ 보다 1-옥탄 선택도면에서 더욱 효과적인 것으로 나타났다. 기상알킬화반응의 경우 Cs 혹은 $NH_4$가 치환된 $H_3PW_{12}O_{40}$ 촉매의 활성은 촉매의 산특성(산점의 비활성화)과 관련이 있었다. 기상알킬화반응에서 반응초기에는 촉매의 강한 산특성 때문에 $C_5-C_7$가 주로 생성되나 반응이 진행되면서 촉매 산점의 비활성화가 진행되어 $C_8$ 및 $+C_9$가 주로 생성되었다. 기상알킬화반응에서 대상 촉매중 $Cs_{2.5}H_{0.5}PW_{12}O_{40}$이 가장 우수한 총수율을 나타내었다.

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Highly Enantioselective Synthesis of a-Alkyl-alanines via the Catalytic Phase-Transfer Alkylation of 2-Naphthyl aldimine tert-butyl ester by using O(9)-Allyl-N(1)-2'3'4'-trifluorobenzylhydrocinchoni

  • Jew, Sang-Sup;Lee, Jeong-Hee;Yoo, Mi-Sook;Lee, Yeon-Ju;Jeong, Byeong-Seon;Park, Boon-Saeng;Kim, Myoung-Goo;Park, Hyeung-Geun
    • 대한약학회:학술대회논문집
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    • 대한약학회 2003년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.1
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    • pp.252.1-252.1
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    • 2003

  • Systematic investigations to develop an efficient enantioselective synthetic method for a-alkyl-alanine by the catalytic phase-transfer alkylation were performed. The alkylation of 2-naphthyl aldimine tert-butyl ester, 1 E with RbOH and O(9)-allyl-N-2'3'4'-trifluorobenzylhydrocinchonidinium bromide, 6, at \ulcorner5 \ulcorner\ulcorner showed the highest enantioselectivities, up to 96％ ee.

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Synthesis of Novel Alkyl $\alpha$-Anilinophenylacetate Derivatives Using Hydrolysis of Hydantoin Ring and Its O-Alkylation

  • Park, Hae-Sun;Park, Myung-Sook;Choi, Hee-Jeon;Kwon, Soon-Kyoung
    • 대한약학회:학술대회논문집
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    • 대한약학회 2003년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.1
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    • pp.244.2-244.2
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    • 2003

  • For the development of new synthetic method for unnatural amino acid esters, alkyl ${\alpha}$-anilinophenylacetates were synthesized through base-catalyzed hydrolysis of 1,5-diphenylhydantoins in methanol and O-alkylation of sodium ${\alpha}$-anilinophenylacetate with alkyl halides in DMF. Even though hydrolysis of hydantoin ring was undertaken under about 30-40$^{\circ}C$ in methanol, the hydantoic acid sodium salt was continuously converted to the sodium ${\alpha}$-anilinophenylacetate. (omitted)

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