- Making Fe(BPBP)-catalyzed C-H and CC oxidations more affordable
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The limited availability of catalytic reaction components may represent a major hurdle for the practical application of many catalytic procedures in organic synthesis. In this work, we demonstrate that the mixture of isomeric iron complexes [Fe(OTf)2(mix-BPBP)] (mix-1), composed of Λ-α-[Fe(OTf)2(S,S-BPBP)] (S,S-1), Δ-α- [Fe(OTf)2(R,R-BPBP)] (R,R-1) and Δ/Λ-β-[Fe(OTf) 2(R,S-BPBP)] (R,S-1), is a practical catalyst for the preparative oxidation of various aliphatic compounds including model hydrocarbons and optically pure natural products using hydrogen peroxide as an oxidant. Among the species present in mix-1, S,S-1 and R,R-1 are catalytically active, act independently and represent ca. 75% of mix-1. The remaining 25% of mix-1 is represented by mesomeric R,S-1 which nominally plays a spectator role in both C-H and C=C bond oxidation reactions. Overall, this mixture of iron complexes displays the same catalytic profile as its enantiopure components that have been previously used separately in sp3 C-H oxidations. In contrast to them, mix-1 is readily available on a multi-gram scale via two high yielding steps from crude dl/meso-2,2′-bipyrrolidine. Next to its use in C-H oxidation, mix-1 is active in chemospecific epoxidation reactions, which has allowed us to develop a practical catalytic protocol for the synthesis of epoxides.
- Yazerski, Vital A.,Spannring, Peter,Gatineau, David,Woerde, Charlotte H.M.,Wieclawska, Sara M.,Lutz, Martin,Kleijn, Henk,Klein Gebbink, Robertus J.M.
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supporting information
p. 2062 - 2070
(2014/03/21)
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- PROCESS FOR THE PREPARATION OF LACTONES OR EPOXIDES
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The present invention relates to a process for the oxidation, in an inert solvent, of a non-aromatic or non-enonic ethylenic bond or of a non-conjugated cyclic ketones into the corresponding epoxides, respectively lactone, using H?2#191O?2#191 as oxidant, a content in water of the reaction medium below 15% w/w and, as sole catalyst, an alkaline or alkaline earth salt or complex.
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- Refining treatment method of liquid reaction mixture obtained from epoxidation reaction of 1,5,9-cyclododecatriene
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After 1,5,9-cyclododecatriene is epoxidized with hydrogen peroxide in the presence of a catalyst containing a tungsten compound, a quaternary onium salt and a mineral acid, to obtain a liquid reaction mixture containing the resultant 1,2-epoxy-5,9-cyclododecadiene, the catalyst, non-reacted hydrogen peroxide and non-reacted 1,5,9-cyclododecatriene and being phase-separated into an oil phase fraction and an aqueous phase fraction, at least the oil phase fraction of the liquid reaction mixture is treated with an aqueous alkali solution to deactivate and remove the non-reacted hydrogen peroxide and the catalyst contained in at least the oil phase fraction.
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- The selectivities and the mechanism on highly efficient epoxidation of olefins with 2,6-disubstituted pyridine N-oxides catalyzed by ruthenium porphyrin
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Several remarkable selectivities in competitive epoxidations using a ruthenium porphyrin/2,6-disubstituted pyridine N-oxide system were observed. The proposal that the active intermediate of this system differed from the trans-dioxo complex of ruthenium porphyrin was indicatesd.
- Ohtake,Higuchi,Hirobe
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p. 2521 - 2524
(2007/10/02)
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- ISOMERIZATION OF TRANS-1,2-EPOXY-CIS,TRANS-5,9-CYCLODODECADIENE, TRANS-1,2-EPOXY-TRANS,TRANS-5,9-CYCLODODECADIENE, AND TRANS-EPOXYCYCLODODECANE TO THE CORRESPONDING KETONES BY THE ACTION OF LITHIUM AND MAGNESIUM IODIDES AND BROMIDES
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The isomerization of trans-1,2-epoxy-cis,trans-5,9-cyclododecadiene, trans-1,2-epoxy-trans,trans-5,9-cyclododecadiene, and trans-epoxycyclododecane by the action of lithium and magnesium iodides and bromides leads to the formation of the corresponding 12-membered cyclic ketones and is not accompanied by ring contraction.
- Zakharkin, L. I.,Guseva, V. V.,Kamernitskii, D. A.,Tsvetkov, V. F.,Likhomanenko, V. A.
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p. 1291 - 1294
(2007/10/02)
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- Epoxidation of Olefins by Cytochrome P-450 Model Compounds: Kinetics and Stereochemistry of Oxygen Atom Transfer and Origin of Shape Selectivity
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An analysis of the mechanism of the lithium hypocrite epoxidation of olefins catalyzed by Mn(TPP)Cl is presented.We have previously reported that the oxygen atom transfer from manganese porphyrin to olefin occurs via an oxo-olefin intermediate whose breakdown is the rate-determining step of the catalytic cycle.Stereochemical and kinetic evidence presented here indicate that both formation of this intermediate and its subsequent breakdown to form epoxide are, in general, concerted processes.The rarely observed loss of stereoselectivity represents the presence of a minor leakage pathway in the breakdown of the oxo-olefin complex to form epoxide.Shape selective olefin epoxidation is achieved when the sterically hindered porphyrin, Mn(TMP)Cl, is used as a catalyst in the hypochlorite system.The observed shape selectivity parallels the large differences in binding energies for formation of the oxo-olefin complex.
- Collman, James P.,Brauman, John I.,Meunier, Bernard,Hayashi, Teruyuki,Kodadek, Thomas,Raybuck, Scott A.
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p. 2000 - 2005
(2007/10/02)
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