13043-55-5Relevant academic research and scientific papers
Synthesis of methyl Β-alkylcarboxylates by Pd/diphosphine-catalyzed methoxycarbonylation of methylenealkanes RCH2CH2C(R)=CH2
Nifant'ev, Ilya E.,Sevostyanova, Nadezhda T.,Batashev, Sergey A.,Vinogradov, Alexey A.,Vinogradov, Alexander A.,Churakov, Andrei V.,Ivchenko, Pavel V.
, p. 123 - 132 (2019)
A series of methylenealkanes RCH2CH2(R)C = CH2 (R = n-butyl, n-hexyl, isopropyl and isobutyl), which are products of selective zirconocene-catalyzed dimerization of α-olefins, were introduced into Pd-catalyzed methoxycarbonylation. With the use of 5-methyleneundecane (1-hexene dimer) as a substrate, the roles of protic acid, Lewis acid and molecular hydrogen were established for model Pd(II)/PPh3 and Pd(II)/diphosphine catalysts. A series of bridged diphosphines were studied as catalyst components L in PdCl2/L-catalyzed methoxycarbonylation in the presence of H2. One of the nine diphosphines studied, trans-2,3-bis(diphenylphosphinomethyl)norbornane, demonstrated the best catalytic results in terms of catalytic activity, selectivity and isolated yields of the products. Under the optimized conditions during 24 h experiments, dimers RCH2CH2(R)C = CH2 were transformed to methyl carboxylates RCH2CH2(R)CHCH2COOMe with 99+% regioselectivity; isolated yields were 62–81%. In that way, the catalytic methoxycarbonylation of synthetically available methylenealkanes is an effective approach to branched carboxylic acids, with high prospects for practical application.
Catalytic oligomerization of α-olefins in the presence of two-stage activated zirconocene catalyst based on 6,6-dimethylfulvene ‘dimer’
Nifant'ev, Ilya E.,Vinogradov, Alexey A.,Vinogradov, Alexander A.,Bezzubov, Stanislav I.,Ivchenko, Pavel V.
, p. 35 - 37 (2017)
Zirconocene obtained from 6,6-dimethylfulvene ‘dimer’, being activated subsequently with triisobutylaluminium and methylalumoxane, catalyzes transformation of α-olefins into a mixture of vinylidene oligomers with minimal losses to isomerization, which allows one to consider this catalyst perspective for the synthesis of branched hydrocarbons with uniform structure.
Highly Efficient and 1,2-Regioselective Method for the Oligomerization of 1-Hexene Promoted by Zirconium Precatalysts with [OSSO]-Type Bis(phenolate) Ligands
Nakata, Norio,Nakamura, Kazuaki,Ishii, Akihiko
, p. 2640 - 2644 (2018)
A mixture of zirconium complex 7, which carries a phenyl-substituted [OSSO]-type bis(phenolate) ligand, and dried modified methylaluminoxane (dMMAO) catalyzes the 1,2-regioselective oligomerization of 1-hexene at relatively low catalyst loadings (0.0056 mol %) to produce the corresponding vinylidene-terminated dimer, 5-methyleneundecane (74-80%), and trimer, 7-butyl-5-methylenetridecane (8-11%). The observed turnover frequencies (TOFs) are relatively high (up to 11a€?100 h-1). When a mixture of 2,6-dimethylphenyl-substituted precatalyst 8 and dMMAO was used, the oligomerization of 1-hexene proceeded effectively to afford predominantly the dimer (87-91%) together with a small amount of the trimer (8-11%) at remarkably high TOFs (up to 6640 h-1).
Zirconocene dichlorides as catalysts in alkene carbo- And cyclometalation by AlEt3: intermediate structures and dynamics
Dzhemilev, Usein M.,Ivchenko, Pavel V.,Khalilov, Leonard M.,Kovyazin, Pavel V.,Mukhamadeeva, Olesia V.,Nifant'ev, Ilya E.,Parfenova, Lyudmila V.
, p. 15802 - 15820 (2021/12/02)
A series of zirconocenes L2ZrCl2 (23 examples) were studied as catalysts in the reaction of alkenes with AlEt3. The catalyst activity and reaction chemoselectivity were found to depend on the ligand structure in the complex and the nature of the solvent. The alkyl exchange in the triethylaluminum dimer was studied by NMR spectroscopy; a solvent effect on the alkyl exchange parameters was established. In the reaction between L2ZrCl2 and AlEt3, the formation of intermediates L2ZrEtCl, L2Zr(μ-Cl)CH2CH2AlEt2, L2Zr(μ-H)CH2CH2AlEt2, and L2Zr(μ-Cl)CH2CH(AlEt2)2 was shown; the ratio of the intermediates depends on the ligand structure in the initial complex and the solvent. The exchange in the ethanediyl bridge ZrCH2CH2Al, proceeding via zirconocenecyclopropane structures, was demonstrated for the first time for five-membered bimetallic complexes L2Zr(μ-Cl)CH2CH2AlEt2 with ansa-ligands (L2 = Me2SiCp2, H2CInd2, Me2CInd2, Me2SiInd2, and C2H4Ind2). Five-membered bimetallic complexes were shown to participate in the formation of cyclic organoaluminum products-3-substituted alumolanes. This journal is
Oxidative Cleavage of Alkenes by O2with a Non-Heme Manganese Catalyst
Bennett, Elliot L.,Brookfield, Adam,Guan, Renpeng,Huang, Zhiliang,Mcinnes, Eric J. L.,Robertson, Craig M.,Shanmugam, Muralidharan,Xiao, Jianliang
supporting information, p. 10005 - 10013 (2021/07/19)
The oxidative cleavage of C═C double bonds with molecular oxygen to produce carbonyl compounds is an important transformation in chemical and pharmaceutical synthesis. In nature, enzymes containing the first-row transition metals, particularly heme and non-heme iron-dependent enzymes, readily activate O2 and oxidatively cleave C═C bonds with exquisite precision under ambient conditions. The reaction remains challenging for synthetic chemists, however. There are only a small number of known synthetic metal catalysts that allow for the oxidative cleavage of alkenes at an atmospheric pressure of O2, with very few known to catalyze the cleavage of nonactivated alkenes. In this work, we describe a light-driven, Mn-catalyzed protocol for the selective oxidation of alkenes to carbonyls under 1 atm of O2. For the first time, aromatic as well as various nonactivated aliphatic alkenes could be oxidized to afford ketones and aldehydes under clean, mild conditions with a first row, biorelevant metal catalyst. Moreover, the protocol shows a very good functional group tolerance. Mechanistic investigation suggests that Mn-oxo species, including an asymmetric, mixed-valent bis(μ-oxo)-Mn(III,IV) complex, are involved in the oxidation, and the solvent methanol participates in O2 activation that leads to the formation of the oxo species.
Diastereoselective synthesis of functionally substituted alkene dimers and oligomers, catalysed by chiral zirconocenes
Kovyazin, Pavel V.,Abdullin, Il'giz N.,Parfenova, Lyudmila V.
, p. 144 - 152 (2018/11/21)
The research addresses the reaction of terminal alkenes and propene with AlR3 (R = Me, Et) in the presence of chiral Zr complexes, rac-[Y(η5-C9H10)2]ZrCl2 (Y = C2H4, SiMe2) or (NMI)2ZrCl2 (NMI- η5–neomenthylindenyl), and methylaluminoxane. The effect of reaction conditions, catalyst and trialkylalane structure on the substrate conversion and the reaction chemo- and stereoselectivity has been studied. The reaction predominantly goes via the stage of alkene methyl(ethyl)zirconation with subsequent introduction of substrate molecules into the Zr-C bond. As a result, a diastereoselective one-pot method for the synthesis of functionally substituted linear terminal alkene dimers and propene oligomers was developed.
Preparation method and application of branched dialkyl alkylphosphonate
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Paragraph 0030-0033; 0078-0081, (2019/10/29)
The invention discloses a preparation method and application of branched dialkyl alkylphosphonate. The method provided by the invention takes an alpha-olefin dimerization product vinylidene olefin anddialkyl phosphite as the raw materials, and carrying ou
Posttreatment technique for SN2 alkylation of aromatics with alkyl halides: Aiming toward large-scale synthesis of building blocks for soft π-molecular materials
Okamoto, Ken,Lu, Fengniu,Nakanishi, Takashi
supporting information, p. 1258 - 1263 (2018/08/24)
Unreacted alkyl halide and byproduct olefin contaminants in products of SN2 alkylation reactions of aromatic compounds can be efficiently removed by sequential posttreatments with a base and a boron compound (sodium borohydride or 9- borabicyclo[3.3.1]nonane), followed by column chromatography on silica gel. These treatments permit large-scale purification of various alkylated aromatics, thereby assisting in the development of soft π-conjugated materials, such as monomers for semiconducting polymers or alkylated π-functional liquids.
Effect of Alcohol Structure on the Kinetics of Etherification and Dehydration over Tungstated Zirconia
Rorrer, Julie,Pindi, Suresh,Toste, F. Dean,Bell, Alexis T.
, p. 3104 - 3111 (2018/09/06)
Linear and branched ether molecules have attracted recent interest as diesel additives and lubricants that can be produced from biomass-derived alcohols. In this study, tungstated zirconia was identified as a selective and green solid acid catalyst for the direct etherification of primary alcohols in the liquid phase, achieving ether selectivities of >94 % for C6–C12 linear alcohol coupling at 393 K. The length of linear primary alcohols (C6–C12) was shown to have a negligible effect on apparent activation energies for etherification and dehydration, demonstrating the possibility to produce both symmetrical and asymmetrical linear ethers. Reactions over a series of C6 alcohols with varying methyl branch positions indicated that substituted alcohols (2°, 3°) and alcohols with branches on the β-carbon readily undergo dehydration, but alcohols with branches at least three carbons away from the -OH group are highly selective to ether. A novel model compound, 4-hexyl-1dodecanol, was synthesized and tested to further demonstrate this structure–activity relationship. Trends in the effects of alcohol structure on selectivity were consistent with previously proposed mechanisms for etherification and dehydration, and help to define possible pathways to selectively form ethers from biomass-derived alcohols.
Structurally uniform 1-hexene, 1-octene, and 1-decene oligomers: Zirconocene/MAO-catalyzed preparation, characterization, and prospects of their use as low-viscosity low-temperature oil base stocks
Nifant'ev, Ilya E.,Vinogradov, Alexander A.,Vinogradov, Alexey A.,Sedov, Igor V.,Dorokhov, Viktor G.,Lyadov, Anton S.,Ivchenko, Pavel V.
, p. 40 - 50 (2017/09/25)
An original approach to α-olefin oligomerization as well as novel thermally stable zirconocene catalysts for use in such reactions has been elaborated. The method reported allows the achievement of fractions of lightweight α-olefin oligomers up to 90% yields without considerable formation of byproducts like internal alkenes, alkanes, and higher oligomers. Trimers, tetramers, and pentamers of 1-hexene, 1-octene, and 1-decene were isolated as individual compounds and were hydrogenated. Viscosity characteristics of the isolated saturated and unsaturated hydrocarbons have been studied at various temperatures. The isolated saturated oligomers of 1-octene and 1-decene outperform the traditional electrophilic oligomerization products in terms of viscosity indexes, pour points, and low-temperature viscosity.
