• Title/Summary/Keyword: dinuclear

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Synthesis of Enantiopure Epoxide Compounds Using Dimeric Chiral Salen Catalyst (이량체구조를 갖는 키랄 살렌 촉매를 이용한 고 광학순도의 에폭사이드 화합물 합성)

  • Kim, Geon-Joong;Kim, Seong-Jin;Li, Wenji;Chen, Shu-Wei;Shin, Chang-Kyo;Thakur, Santosh S.
    • Korean Chemical Engineering Research
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    • v.43 no.6
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    • pp.647-661
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    • 2005
  • The stereoselective synthesis of chiral terminal epoxide is of immense academic and industrial interest due to their utility as versatile starting materials as well as chiral intermediates. In this review, we investigate the research and development trend in the asymmetric ring opening reactions using cobalt salen catalysts. Hydrolytic kinetic resolution (HKR) technology is the very prominent way to prepare optically pure terminal epoxides among available methods. We have synthesized homogeneous and heterogeneous chiral dinuclear salen complexes and demonstrated their catalytic activity and selectivity for the asymmetric ring opening of terminal epoxides with variety of nucleophiles and for asymmetric cyclization to prepare optically pure terminal epoxides in one step. The resolved ring opened product combined with ring closing in the presence of base and catalyst afforded the enantioriched terminal epoxides in quantitaive yield. Potentially, these catalysts are using on an industrial scale to produce chiral intermediates. The experimental results of HKR technology applied to the synthesis of various chiral compounds are presented in this paper.

Studies of Oxo-Nitrosyl Complexes(Ⅱ) Synthesis and Properties of Tungsten Oxo-Nitrosyl Complexes with Butylamidoxime Derivatives (산소-니트로실 착물의 연구 (제2보) 부틸아미드옥심 유도체의 텅스텐 산소-니트로실 착물의 합성과 특성)

  • Roh, Soo Gyun;Oh, Sang Oh
    • Journal of the Korean Chemical Society
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    • v.39 no.11
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    • pp.856-862
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    • 1995
  • The tungsten oxo-nitrosyl complexes (n-Bu4N)2[W5O12(NO)2{RC(NH2)NHO}2{RC(NH)NO}2] (R=(CH3)2CH, CH3CH2CH2, CH3SCH2) have been synthesized by the reactions of polyoxotungsten complex (n-Bu4N)2[W6O19] and tungsten dinitrosyl monomeric complex [W(NO)2(acac)(CH3CN)2](BF4) with butylamidoxime derivatives. The prepared complexes have been characterized by elemental analysis, infrared, UV-visible, 1H NMR and 13C NMR spectroscopy. The pentanuclear species was formed by the interaction of the electron-withdrawing {W(NO)2}2+ unit between the two dinuclear tungsten {W2O5}2+ cores. We can estimate to exist large proton interactions viewed from the four doublet in 1H NMR spectrum of (n-Bu4N)2[W5O12(NO)2{(CH3)2CHC(NH2)NHO}2{(CH3)2CHC(NH)NO}2]. We also drew informations of the two different coordination mode and symmetry of the complexes because two ligands appear in 13C NMR spectra instead of four. The {W(NO)2}2+ unit has been cis-form and C2v symmetry in geometric structure.

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Synthesis and Properties of Molybdenum and Tungsten Oxo-Nitrosyl Complexes of Methylthioamidoxime (산소-니트로실 착물의 연구(제3보): 티오메틸아미드옥심의 몰리브덴과 텅스텐 산소-니트로실 착물의 합성과 특성)

  • Roh, Soo Gyun;Oh, Sang Oh
    • Journal of the Korean Chemical Society
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    • v.40 no.1
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    • pp.28-36
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    • 1996
  • The pentanuclear complexes have been obtained by the reactions of molybdenum(VI) and tungsten(VI) polynuclear complexes with molybdenum(O) and tungsten(O) dinitrosyl mononuclear complexes, and methylthioamidoxime. The prepared complexes (n-Bu4N)2[Mo4O12Mo(NO)2{CH3SCH2C(NH2)NHO}2{CH3SCH2C(NH)NO}2](1), (n-Bu4N)2[W4O12Mo(NO)2{CH3SCH2C(NH2)NHO}2{CH3SCH2C(NH)NO}2](2), (n-Bu4N)2[Mo4O12W (NO)2{CH3SCH2C(NH2)NHO}2{CH3SCH2C(NH)NO}2] (3) have been characterized by elemental analysis, infrared, UV-visible and 1H NMR spectra. The complexes are elucidated the cis-{M(NO)2}2+(M = Mo, W) unit and a slight delocalization by spectroscopy. The structure of (n-Bu4N)2[W4O12Mo(NO) 2{CH3SCH2C(NH2)NHO}2{CH3SCH2C(NH)NO}2] was determined by X-ray single crystal diffraction. Crystal data are follows: Monoclinic, $P21}a$, a = 22.14(2) $\AA$, b = 14.93(1) $\AA$, c = 23.20(1) $\AA$, $\beta$ = 111.08(6) $\AA$, V = 7155(9) $\AA$, Z = 4, final R = 0.072 for 6191(I > $3\sigma(I)).$ The structure of complex forms two dinuclear [W2O5{CH3SCH2C(NH2)NHO}{CH3SCH2C(NH)NO}] and a central {Mo(NO)2} 2+ core. The geometric structure of the {Mo(NO)2} 2+unit is the formally cistype and C2v symmetry.

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