- Asymmetric Epoxidation of Enones Promoted by Dinuclear Magnesium Catalyst
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Asymmetric synthesis with cheaper and non-toxic alkaline earth metal catalysts is becoming an important and sustainable alternative to conventional catalytic methodologies mostly relying on precious metals. In spite of some sustainable methods for enantioselective epoxidation of enones, the development of a well-defined and efficient catalyst based on magnesium complexes for these reactions is still a challenging task. In this perspective, we present the application of chiral dinuclear magnesium complexes for asymmetric epoxidation of a broad range of electron-deficient enones. We demonstrate that the in situ generated magnesium-ProPhenol complex affords enantioenriched oxiranes in high yields and with excellent enantioselectivities (up to 99% ee). Our extensive study verifies the literature data in this area and provides a step forward to better understand the factors controlling the oxygenation process. Elaborated catalyst offers mild reaction conditions and a truly wide substrate scope. (Figure presented.).
- Jaszczewska-Adamczak, Joanna A.,Mlynarski, Jacek
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supporting information
p. 4247 - 4255
(2021/07/17)
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- Quest for Efficient Catalysts based on Zinc tert-Butyl Peroxides for Asymmetric Epoxidation of Enones: C2- vs C1-Symmetric Auxiliaries
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Zinc tert-butyl peroxide-based catalysts for the asymmetric epoxidation of enones using tert-butyl hydroperoxide as an oxidant have been developed. A comparative study of chiral monoanioninc N,N′-bidentate ligands, C2-symmetric bisoxazolinates and C1-symmetric enaminooxazolinates, revealed excellent performance of C1-symmetric auxiliary ligands on catalytic asymmetric epoxidation of enones (up to 96% yield, 91% ee).
- Raheem Keeri, Abdul,Justyniak, Iwona,Jurczak, Janusz,Lewiński, Janusz
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supporting information
p. 864 - 868
(2016/04/05)
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- Epoxidation by sodium chlorite with aldehyde-promoted chlorine dioxide formation
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An improved method is described for selective room temperature epoxidation of alkenes by sodium chlorite in a solvent mixture of ethanol, acetonitrile, and water buffered at pH 7. In addition, the use of aldehydes as promoters in chlorite oxidations is described for the first time. The amount of sodium chlorite, the solvent mixture, and the addition of formaldehyde as a practical promoter were optimized. Styrene was used as a test substrate in the optimization studies and the generality of the method was assessed by using a variety of nucleophilic and electrophilic substrates. Yields up to 89% were obtained with styrene and other nucleophilic alkenes are readily converted into epoxides.
- Jangam, Ashok,Richardson, David E.
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scheme or table
p. 6481 - 6484
(2011/02/22)
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- Epoxidation of 1,4-diaroyl ethene derivatives in the presence of UHP or H2O2
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Hydrogen peroxide (H2O2) or urea-hydrogen peroxide (UHP) in basic media react with carbon-carbon double bonds of 1,4-diaroyl ethenes to produce the corresponding epoxides. Copyright Taylor & Francis Group, LLC.
- Mahmoodi, Nosrat O.,Yazdanbakhsh, Mohammad R.,Ghanbari, Fateme
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experimental part
p. 3181 - 3185
(2010/11/20)
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- Unprecedented direct oxygen atom transfer from hypervalent oxido-λ3-iodanes to α,β-unsaturated carbonyl compounds: Synthesis of α,β-epoxy carbonyl compounds
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Tetra-n-butylammonium oxido-λ3-iodane, prepared from 1-hydroxy-1,2-benziodoxol-3(1H)-one by reaction with tetra-n-butylammonium fluoride, directly undergoes oxygen atom transfer to γ,β-unsaturated carbonyl compounds, yielding epoxides.
- Ochiai, Masahito,Nakanishi, Akinobu,Suefuji, Takashi
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p. 2923 - 2926
(2007/10/03)
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- Epoxidation of 2-Butene-1,4-diones with Hydrogen Peroxide in the Presence of a Catalytic Amount of Quaternary Ammonium Iodide
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The epoxidation of 1,4-disubstituted 2-butene-1,4-diones with 30percent aq.H2O2 in the presence of a catalytic amount of quaternary ammonium iodide afforded 2,3-epoxy-1,4-butanediones in high yield.
- Sayama, Shinsei,Inamura, Yutaka
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p. 1993 - 1995
(2007/10/02)
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- Stereospecific Epoxidation of cis-2-Butene-1,4-diones to cis-2,3-Epoxybutane-1,4-diones with Oxodiperoxomolybdenum (VI), MoO5*H2O*HMPA
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The epoxidation of cis-2-butene-1,4-diones 4 with (aqua)(hexamethylphosphoramide)oxodiperoxomolybdenum (VI), MoO5*H2O*HMPA, occured stereospecifically to give the cis-epoxides 5, whose stereochemistry was assigned on the basis of chemical evidence and a comparision of their spectral data with those of the corresponding trans-epoxides 6, which were prepared by the epoxidation of the trans-olefins 3 with alkaline hydrogen peroxide.
- Chien, Chun-Sheng,Kawasaki, Tomomi,Sakamoto, Masanori,Tamura, Yasumitsu,Kita, Yasuyuki
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p. 2743 - 2749
(2007/10/02)
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- The Reaction of Chlorosulfonyl Isocyanate with Epoxides. A Novel Conversion of Epoxides to Cyclic Carbonates
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The facile reaction of chlorosulfonyl isocyanate (CSI) with epoxides is described.The initially formed 2-chlorosulfonylimino-1,3-dioxolane 2a-e and N-chlorosulfonyl-1,3-oxazolidin-2-one 3a-e derivatives undergo smooth hydrolysis to yield the corresponding 1,3-dioxolan-2-one 4a-e and 1,3-oxazolidin-2-one 5a-e derivatives respectively.This reaction sequence provides a convenient one-pot method for the conversion of epoxides to cylic carbonates.Substrates such as 1g-i are exceptions to this otherwise general reaction pathway.
- Keshava Murthy, K. S.,Dhar, D. N.
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p. 1721 - 1725
(2007/10/02)
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- PHOTOSENSITIZED Oxidation of Furans. Part 4. Influence of the Substituents on the Behaviour of the endo-Peroxides of Furans
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A comparison of the ehaviour of endo-peroxides of the β-furoic esters (1a, b and d-f) and of the furans (1c or g), with the same 2,5-substituents, shows that the thermal instability of these compounds is related to the electron density in the bicyclic unsaturated ring.This also accounts for the higher stability of the alkyl-substituted endo-peroxides (1a-c) as compared with that of the aryl-substituted derivatives (1d-g), as well as for the different course of the thermal conversion in the two series.
- Graziano, M. Liliana,Iesce, M. Rosaria,Scarpati, Rachele
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p. 2007 - 2012
(2007/10/02)
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