6434-78-2Relevant academic research and scientific papers
Extension of surface organometallic chemistry to metal?organic frameworks: Development of a well-defined single site [(≡Zr? O?)W(=O)(CH2TBu)3] olefin metathesis catalyst
Thiam, Zeynabou,Abou-Hamad, Edy,Dereli, Busra,Liu, Lingmei,Emwas, Abdul-Hamid,Ahmad, Rafia,Jiang, Hao,Isah, Abdulrahman Adamu,Ndiaye, Papa Birame,Taoufik, Mostafa,Han, Yu,Cavallo, Luigi,Basset, Jean-Marie,Eddaoudi, Mohamed
supporting information, p. 16690 - 16703 (2020/11/09)
We report here the first step by step anchoring of a W(≡CtBu)(CH2tBu)3 complex on a highly crystalline and mesoporous MOF, namely Zr-NU-1000, using a Surface Organometallic Chemistry (SOMC) concept and methodology. SOMC allowed us to selectively graft the complex on the Zr6 clusters and characterize the obtained single site material using state of the art experimental methods including extensive solid-state NMR techniques and HAADF-STEM imaging. Further FT?IR spectroscopy revealed the presence of a W=O moiety arising from the in situ reaction of the W≡CtBu functionality with the coordinated water coming from the 8-connected hexanuclear Zr6 clusters. All the steps leading to the final grafted molecular complex have been identified by DFT. The obtained material was tested for gas phase and liquid phase olefin metathesis and exhibited higher catalytic activity than the corresponding catalysts synthesized by different grafting methods. This contribution establishes the importance of applying SOMC to MOF chemistry to get well-defined single site catalyst on MOF inorganic secondary building units, in particular the in situ synthesis of W=O alkyl complexes from their W carbyne analogues.
Carbonylative, Catalytic Deoxygenation of 2,3-Disubstituted Epoxides with Inversion of Stereochemistry: An Alternative Alkene Isomerization Method
Lamb, Jessica R.,Hubbell, Aran K.,MacMillan, Samantha N.,Coates, Geoffrey W.
supporting information, p. 8029 - 8035 (2020/05/01)
Reactions facilitating inversion of alkene stereochemistry are rare, sought-after transformations in the field of modern organic synthesis. Although a number of isomerization reactions exist, most methods require specific, highly activated substrates to achieve appreciable conversion without side product formation. Motivated by stereoinvertive epoxide carbonylation reactions, we developed a two-step epoxidation/deoxygenation process that results in overall inversion of alkene stereochemistry. Unlike most deoxygenation systems, carbon monoxide was used as the terminal reductant, preventing difficult postreaction separations, given the gaseous nature of the resulting carbon dioxide byproduct. Various alkyl-substituted cis- A nd trans-epoxides can be reduced to trans- A nd cis-alkenes, respectively, in >99:1 stereospecificity and up to 95% yield, providing an alternative to traditional, direct isomerization approaches.
Photocatalytic Transfer Hydrogenolysis of Allylic Alcohols on Pd/TiO2: A Shortcut to (S)-(+)-Lavandulol
Takada, Yuki,Caner, Joaquim,Kaliyamoorthy, Selvam,Naka, Hiroshi,Saito, Susumu
supporting information, p. 18025 - 18032 (2017/12/08)
We report herein a regio- and stereoselective photocatalytic hydrogenolysis of allylic alcohols to form unsaturated hydrocarbons employing a palladium(II)-loaded titanium oxide; the reaction proceeds at room temperature under light irradiation without stoichiometric generation of salt wastes. Olefin and saturated alcohol moieties tolerated the reaction conditions. Hydrogen atoms were selectively incorporated into less sterically congested carbons of the allylic functionalities. This protocol allowed a short-step synthesis of (S)-(+)-lavandulol from (R)-(?)-carvone by avoiding otherwise necessary protection/deprotection steps.
METHOD FOR PRODUCING ORGANIC COMPOUND
-
Paragraph 0111-0112; 0115, (2018/10/16)
PROBLEM TO BE SOLVED: To provide a method of subjecting a compound having on one carbon atom a carbon atom constituting a carbon-carbon double bond and a functional group such as a hydroxyl group to a reductive reaction condition and producing an organic compound having the functional group substituted with a hydrogen atom. SOLUTION: There is provided a method for producing a compound represented by a formula (50) from a raw material compound represented by a formula (10). The method includes a step of irradiating a reaction system with light, the reaction system comprising the raw material compound, a hydrogen source compound, and a catalyst having a palladium component supported by a carrier containing titanium oxide. (R11 to R15 are a hydrogen atom, a hydrocarbon group having 1 to 40 carbon atoms which may have a cyclic structure or a derivative group thereof, or a heteroatom-containing group having 1 to 20 carbon atoms which may have a cyclic structure or a derivative group thereof; and R16 is a hydrogen atom, a hydrocarbon group having 1 to 40 carbon atoms or an acyl group having 1 to 20 carbon atoms which may have a cyclic structure, or -CH(CH2OH)2).) COPYRIGHT: (C)2015,JPO&INPIT
β-Diketiminate complexes of Group 4: Active complexes for the isomerization of α-olefins and the polymerization of propylene towards elastomeric polypropylene
Shaviv, Ella,Botoshansky, Mark,Eisen, Moris S.
, p. 165 - 180 (2007/10/03)
The β-diketiminate lithium ligand [{N(SiMe3)C(Ph)} 2CH][Li] reacted with Group 4 metal salts (Ti and Zr) to yield the complexes [{N(SiMe3)C(Ph)}2CH] 2TiCl2 (5) and [{N(SiMe3)C(Ph)} 2CH][N(SiMe3)C(Ph)NC(Ph)CH(SiMe3)] ZrCl2 (6). The crystal structure of 6 shows that one of the two ketamidinate ligands undergoes an isomerization to the corresponding substituted benzamidinate. A mechanism for the catalyzed isomerization of the β-diketiminate ligand is presented. Complex 5 was found to be active in the polymerization of propylene, producing remarkably high-molecular weight (>100,000 g mol-1) elastomeric polymer, whereas the zirconium complex was found inactive. Complex 5, and surprisingly complex 6, were found to be active catalysts, in the presence of MAO (methylalumoxane), for the isomerization of aliphatic olefins (1-octene, allylbenzene). Each complex catalyzed the olefins by different mechanisms. Kinetic studies for the isomerization of allylbenzene by complex 5 show that the reaction rate follows a first order in both catalyst and olefin concentrations with Δ H ?=14.7(4) kcal mol-1 and Δ S ?=-33(1) e.u. These findings support the epimerization mechanism of the last inserted monomer that is proposed for as the primary cause for the elastomeric properties of polypropylene produced by this complex. In addition, we show how complementary isomerization studies of α-olefins shed light on the polymerization mechanism.
Intramolecular Dehydration of β-Hydroxyalkylphosphonic Acid Monoesters. A Novel Type of Olefin Formation
Kawashima, Takayuki,Nakamura, Mio,Nakajo, Akira,Inamoto, Naoki
, p. 1483 - 1486 (2007/10/02)
The title reaction using dicyclohexylcarbodiimide (DCC) gave stereospecifically the corresponding olefins in good yields via tetracoordinate 1,2-oxaphosphetanes.Use of more than one equivalent of DCC afforded better yields of the olefin.
A Bridged Tetrahydrophosphole Ylide Derived from 9-Phenylphosphabicyclononane: A Reagent for E-Selective Wittig Reactions
Vedejs, E.,Peterson, M. J.
, p. 1985 - 1986 (2007/10/02)
The bicyclic ylide 4 reacts with aldehydes to afford the E-alkenes.Selectivity is 94 - 6percent E for unbranched aldehydes, but the selectivity decreases with increasing α-branching.Ylide 4 is the first E-selective, nonstabilized ylide that allows efficient utilization of the P-alkyl substituent.
Alkyliron and Alkylcobalt Reagents, VII. - On the Substitution of the Halogen of Alkenyl Chlorides, Alkenyl Fluorides, and Alkynyl Halides by Reagents of the Type R4MLi2 (M = Fe, Co)
Kauffmann, Thomas,Saelker, Reiner,Voss, Karl-Uwe
, p. 1447 - 1452 (2007/10/02)
Me4FeLi2 and Me4CoLi2, which are favourable reagents for the substitution of Br in alkenyl bromides, also proved to be favourable for the substitution of the halogen in alkenyl chlorides (yields 68-99 percent; nearly complete retention of configuration in the case of Me4FeLi2), β-fluorostyrene (best yield 92 percent), and 1-fluoronaphthalene (best yield 47 percent).Me4FeLi2 differentiates between various alkenyl chlorides in 1:1 competition experiments better than Me4CoLi2 and is the optimal reagent for the substitution of halogen in 1-chloro-2-phenylethyne (12), 1-bromo-2-phenylethyne (13), and 1-chloro-3-phenoxypropyne (15) by methyl (yields 70, 46, and 80 percent, respectively).Substitution of the halogen in 12 by the n-butyl, n-octyl, and phenyl residue is better achieved by the catalytic systems RMgBr + 2.5 mol percent FeCl2 (R = nBu, nOct, Ph; yields 75, 63, and 96 percent, respectively) than by the reagents nBu4FeLi2, nBu4Fe(MgBr)2, nOct4Fe(MgBr)2, or Ph4Fe(MgBr)2 (yields 18-28 percent). Key Words: Iron, organo complexes / Cobalt, organo complexes
THE HYDRIDOPENTACYANOCOBALTATE ANION INDUCED DEOXYGENATION OF ALLYLIC ALCOHOLS USING β-CYCLODEXTRIN AS A PHASE TRANSFER AGENT
Lee, Jong-Tae,Alper, Howard
, p. 4101 - 4104 (2007/10/02)
β-Cyclodextrin promotes the deoxygenation of allylic alcohols to olefins using hydrogen and the in situ generated hydridopentacyanocobaltate anion.Internal olefins, of trans-stereochemistry, are the principal reaction products (i. e., no cis-products are formed).
Organoborane-Catalyzed Hydroalumination of Terminal Allenes
Nagahara, Shigeru,Maruoka, Keiji,Doi, Yoshiharu,Yamamoto, Hisashi
, p. 1595 - 1598 (2007/10/02)
Organoborane-catalyzed hydroalumination of terminal allenes with dichloroaluminum hydride gives rise to the corresponding allylaluminum compounds under mild conditions with high regioselectivity.
