Samarium Metal in Organic Synthesis

Banik, Bimal K.

doi:10.1002/1099-0690(200208)2002:15<2431::aid-ejoc2431>3.0.co;2-h

Cited by 68 publications

(17 citation statements)

References 26 publications

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“…Eine davon ist die einfache Diastereoselektivität (3,4‐ syn ‐ gegenüber 3,4‐ anti ‐Selektivität). Um eine meso ‐Verbindung wie 93 oder 94 zu erhalten, bedarf es einer 3,4‐ anti ‐Anordnung, und genau dies wird in den meisten beschriebenen Pinakol‐Kupplungsreaktionen nicht begünstigt 46. 47…”

Section: Die Konvergente Vorgehensweiseunclassified

Peroxometalates Immobilized on Magnetically Recoverable Catalysts for Epoxidation

Qiao¹,

Li²,

Li³

et al. 2012

ChemPlusChem

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Magnetically separable catalysts were prepared and employed for the epoxidation of olefins with hydrogen peroxide. In all cases the magnetic core was firstly covered with a silica layer to prevent iron ion-initiated decomposition of hydrogen peroxide. The catalytic active species, an ionic liquid-type peroxotungstate, was then immobilized either by hydrogen bonding (catalyst 1) or by covalent SiO linkage (catalyst 2). In addition to a thorough characterization by FT-IR, XRD, NMR, DRIFT, XPS, and TEM, the catalytic potential was evaluated in the epoxidation of a variety of olefins as well as allylic alcohols. Both catalysts showed essentially a constant activity after at least ten consecutive cycles. On the basis of the research above, a new type of magnetically separable catalyst was constructed by immobilization of lacunary-type phosphotungstate by hydrogen bonding between the sulfonate anion and silanol group on the surface of the core–shell magnetic nanoparticles. After the detailed characterization, the catalyst was used in the epoxidation of a variety of olefins and allylic alcohols and was found to possess high activity, selectivity towards epoxides, and a constant activity after at least ten catalytic recycles without solvent

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Section: Die Konvergente Vorgehensweiseunclassified

Peroxometalates Immobilized on Magnetically Recoverable Catalysts for Epoxidation

Qiao¹,

Li²,

Li³

et al. 2012

ChemPlusChem

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“…One such type is simple diastereoselectivity (3,4‐ syn versus 3,4‐ anti ). The formation of compounds 93 ( meso‐ I) and 94 ( meso ‐II) requires a 3,4‐ anti arrangement, which is disfavored in most reported pinacol coupling reactions 46. 47…”

Section: The Convergent Approachmentioning

confidence: 99%

Proton affinity of proline and modified prolines using the kinetic method: role of the conformation investigated by ab initio calculations

Mezzache¹,

Afonso²,

Pèpe³

et al. 2003

Rapid Comm Mass Spectrometry

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The proton affinities of proline, cis-3-methylproline and cis-3-ethylproline have been measured by the kinetic method using an ion trap instrument; the values obtained are 936, 940.5, and 943 kJ mol(-1), respectively. The experimental values are consistent with those obtained by high-level ab initio calculations (B3LYP/6-31+G*//B3LYP/6-31G* and B3P86/6-31+G*//B3LYP/6-31G*). Several conformations of neutral and protonated proline were considered, in particular the endo and exo ring structure and the position of the carboxyl group. These results show the importance of the position of the hydrogen atom of the carboxyl group in determining the most stable protonated proline structure.

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“…Long‐term preservation of SmI 2 is another difficulty owing to its sensitity to air and moisture. By comparison, the direct use of samarium metal has the advantages of simple operation, atom economy, cheap and easy storage –…”

Section: Methodsmentioning

confidence: 99%