- Use of CuO encapsulated in mesoporous silica SBA-15 as a recycled catalyst for allylic C-H bond oxidation of cyclic olefins at room temperature
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CuO nanoparticles were deposited on SBA-15 in three routes. These were metal loading on SBA-15 and calcination at 550 °C (Cu-SBA-15), metal loading on 3-aminopropyl-trimethoxysilane grafted SBA-15 and calcination at 550 °C (Cu-N-SBA-15), and metal loading
- Samadi, Saadi,Ashouri, Akram,Ghambarian, Mehdi
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- Cu(CH3CN)4PF6 immobilized on halloysite as efficient heterogeneous catalyst for oxidation of allylic C–H bonds in olefins under mild reaction condition
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Considering the importance of oxidation of allylic C–H bonds in olefins and the unresolved challenging issues, such as long reaction time and the large quantity of catalyst required, and encouraged by the excellent performance of halloysite as a catalyst
- Sadjadi, Samahe,Samadi, Saadi,Samadi, Mojgan
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- 2-Aminopyrazine-functionalized MCM-41 nanoporous silica as a new efficient heterogeneous ligand for Cu-catalyzed allylic C–H bonds oxidation of olefins
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In spite of the importance of the application of allylic C–H bond oxidation of olefins in organic synthesis and existence of the numerous reports, lots of limitations such as large excess of the olefin respect to the oxidant, low chemical yield, long time of reaction and a large amount of the catalyst were reminded. We introduced a novel catalytic system using functionalized MCM-41 as catalyst support to promote efficiency of this reaction. The heterogeneous ligand Pyr-MCM-41 was prepared by substituted 2-aminopyrazine ligand on functionalized MCM-41 with 3-chloropropyltrimthoxysilane and characterized by FT-IR, XRD, SEM, EDX, BET, TGA, CHN techniques. In situ immobilized Pyr-MCM-41 by copper (I) trifluoromethanesulfonate (CuOTf) was applied in direct catalytic esterification of inert C–H bonds in olefins using various peresters at room temperature.
- Samadi, Saadi,Ashouri, Akram,Kamangar, Shadi,Pourakbari, Fatemeh
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p. 557 - 569
(2019/11/03)
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- Catalytic enantioselective allylic oxidation of olefins with copper(I) catalysts and new perester oxidants
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Asymmetric allylic oxidation of cyclic olefins using a catalytic amount of copper(I) bisoxazoline complexes and new peresters was investigated to give allylic benzoate esters in high selectivity (~80%ee), yield (70-80%), and at reasonable rates (5-7 d) at
- Andrus, Merritt B.,Chen, Xi
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p. 16229 - 16240
(2007/10/03)
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- The Influence of Remote Heteroatom Substituents on the Stereoselectivity of Cyclopentene Ozonolysis
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The stereoselectivity for ozonide formation from cyclopentenes with allylic heteroatom substituents has been examined.Silyl ethers give high selectivity in favor of the exo-substituted ozonide, while esters of 2-cyclopentenol form ozonide mixtures with little stereoselection.Trapping experiments establish that fragmentation of the primary ozonides is highly regioselective to give only one of the isomeric ω-oxo carbonyl oxide intermediates and that the variation in final ozonide stereochemistry results from differing interactions between the remote substituent groupsand the carbonyl oxide system during cyclization of this intermediate.The effect of substituent and solvent on ozonide stereochemistry suggests a dominant role for electrostatic repulsion between carbonyl oxide and the heteroatom substituent during intramolecular cycloaddition.A chair-like transition state is proposed for this process and is in accord with the increase in exo selectivity for derivatives of 2-methyl-2-cyclopentenol.
- Bunnelle, William H.,Isbell, Terry A.
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p. 729 - 740
(2007/10/02)
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- Nucleophilic substitution of 5,5-dimethyl-2-cyclopentenyl derivatives. Lack of SN2' reaction
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Treatment of tetramethyl-1,3-cyclobutadienone with two equivalents of allyl oxide anion at 140 deg C yields 2,2-dimethyl-4-pentenoic acid which is cyclized via the acid chloride whith aluminium chloride to 5,5-dimethyl-2-cyclopentenone 4.Reduction of 4 with aluminium hydride provides 5,5-dimethyl-2-cyclopentenol 1-OH which is pyrolyzed to 5,5-dimethyl-1,3-cyclopentadiene in dimethylsulfoxide.Reduction of 4 with tri-t-butoxyaluminium hydride at -70 deg C gives 2,2-dimethylcyclopentanone.The 2,6-dichlorobenzoate ester of 1-OH failed to yield SN2' products under a variety of conditions.The rate constants for solvolysis of the p-nitrobenzoate esters of 1-OH, 2-cyclopentenol and Z-2-methyl-4-hexene-3-ol in 80 percent ethanol at 80 deg C are 20.2, 523, and 0.63 x 1E-6s-1, respectively, and the main products of solvolysis are 5-ethoxy-3,3-dimethylcyclopentene, 3-ethoxycyclopentene, and E-2-ethoxy-5-methyl-3-hexene, respectively.There is steric hindrance to solvatation during ionization of the p-nitrobenzoate of 1-OH.
- Kopecky, Karl R.,Levine, Cyril
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p. 3273 - 3279
(2007/10/02)
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