1205-84-1Relevant articles and documents
Thermal defect engineering of precious group metal-organic frameworks: Impact on the catalytic cyclopropanation reaction
Heinz, Werner R.,Junk, Raphael,Agirrezabal-Telleria, Iker,Bueken, Bart,Bunzen, Hana,G?lz, Thorsten,Cokoja, Mirza,De Vos, Dirk,Fischer, Roland A.
, p. 8077 - 8085 (2020)
We report on the engineering of defects in precious group metal (PGM)-based HKUST-1 (Hong Kong University of Science and Technology) analogues (RhII,II, RuII,II, RuII,III) and the ramification on the catalytic activity by using the cyclopropanation of styrene with ethyl diazoacetate (EDA) as an analytical probe to investigate complex metal-organic framework (MOF) structures. We have characterized the active sites within the extended frameworks by their activity, product distribution and stereoselectivity. The role of the metal, its oxidation state and the availability of open metal sites is elucidated. With a set of 17 samples including reference to Cu-HKUST-1, metal nanoparticles and existing literature, conclusions on the tuneability of paddlewheel complexes within self-supported porous and crystalline frameworks are presented. In particular, additional axial ligands (OAc-/Cl-) accounting for charge compensation at the mixed-valent RuII,III nodes seem responsible for side-product formation during catalysis. Thermal defect-engineering allows for controlled and preferential removal of those axial ligands accompanied by reduction of the average metal oxidation state. This enhances the number of open metal sites (OMS) and the catalytic activity as well as improving the chemoselectivity towards cyclopropanes. The preference towards formation of trans-cyclopropane is assigned to the steric crowding of the paddlewheel moiety. This diastereoselectivity gradually diminishes with rising defectiveness of the PGM-HKUST-1 analogues featuring modified paddlewheel nodes.
Palladium(0)-Catalyzed Alkoxycarbonylation of Allyl Phosphates and Acetates
Murahashi, Shun-Ichi,Imada, Yasushi,Taniguchi, Yuki,Higashiura, Shinya
, p. 1538 - 1545 (1993)
Palladium-catalyzed alkoxycarbonylation of allyl phosphates under CO (1 atm) at 50 deg C proceeds highly efficiently to give the corresponding β,γ-unsaturated esters.The carbonylation of geranyl phosphate ((E)-11) under CO (1 atm) at 50 deg C gave ethyl ester of homogeranic acid ((E)-12) stereoselectively.The carbonylation takes place at least substituted allylic positions with inversion of configuration.Typically, the methoxycarbonylation of cis-5-(methoxycarbonyl)-2-cyclohexen-1-yl phosphate (cis-16) gave trans-dimethyl-2-cyclohexene-1,5-dicarboxylate (trans-17) selectively.Alkoxycarbonylation of allyl acetates is performed for the first time in the presence of a catalytic amount of bromide ion.The reaction can be rationalized by assuming the mechanism which involves oxidative addition of palladium(0) species to allyl acetates to give ?-allylpalladium acetate, fast ligand exchange of the acetate with bromide, insertion of carbon monoxide to give acylpalladium species, and alkoxylation.
SUBSTITUTION NUCLEOPHILE VINYLIQUE PAR LE REACTIF DE REFORMATSKY CATALYSSE PAR DES COMPLEXES DU NICKEL ET DU PALLADIUM ZEROVALENTS. SYNTHESE D'ESTERS β,γ-ETHYLENIQUES
Fauvarque, J.F.,Jutand, A.
, p. 109 - 114 (1981)
Zerovalent complexes of palladium and nickel catalyse vinylic nucleophilic substitution by the Reformatsky reagent giving β,γ-ethylenic esters.Formation of a ?-vinylpalladium complex is the rate-determining step of the reaction.
Iridium complex-catalyzed carbonylation of allylic phosphates
Takeuchi, Ryo,Akiyama, Yasushi
, p. 137 - 145 (2002)
[Ir(cod)Cl]2 with a ligand such as P(2-furyl)3, PPh2C6F5 or AsPh3 showed high catalytic activity for the carbonylation of allylic phosphates in the presence of alcohols to give the corresponding β,γ-unsaturated esters. The carbonylation of diethyl (E)-3-phenyl-2-propenyl phosphate in the presence of EtOH under an initial carbon monoxide pressure of 40 kg cm-2 at 100°C gave ethyl (E)-4-phenyl-3-butenoate in 90% yield. No (Z)-isomer was obtained. The reaction proceeded smoothly without using an amine as an additive. The carbonylation of 2-alkenyl diethyl phosphates in the presence of EtOH gave a mixture of ethyl (E)- and (Z)-3-alkenoate. The stereochemistry of the starting material was lost by syn-anti isomerization of the π-allyl iridium intermediate prior to the insertion of carbon monoxide into the iridium-carbon bond. Increasing the steric bulkiness of the substituent at the γ-position of the allyl system or increasing the initial carbon monoxide pressure increased the selectivity for a product with the same stereochemistry as the starting material.
Common precursor strategy for the synthesis of bestatin, amprenavir intermediate and syn-4-hydroxy-5-phenyl-γ-lactam
Kumar, Brijesh,Aga, Mushtaq A.,Rouf, Abdul,Shah, Bhahwal A.,Taneja, Subhash C.
, p. 17206 - 17209 (2014)
A common precursor strategy for the synthesis of bestatin hydrochloride, an anticancer agent, 1,3-diaminoalcohol, an amprenavir intermediate, and a syn-4-hydroxy-5-phenyl-γ-lactam intermediate of various bioactive molecules using an α,β-unsaturated ester as a common precursor is described. The protocol offers mild reaction conditions, good yields and excellent stereoselectivity.
Ligand-Controlled Palladium-Catalyzed Alkoxycarbonylation of Allenes: Regioselective Synthesis of α,β- and β,γ-Unsaturated Esters
Liu, Jie,Liu, Qiang,Franke, Robert,Jackstell, Ralf,Beller, Matthias
, p. 8556 - 8563 (2015)
The palladium-catalyzed regioselective alkoxycarbonylation of allenes with aliphatic alcohols allows to produce synthetically useful α,β- and β,γ-unsaturated esters in good yields. Efficient selectivity control is achieved in the presence of appropriate ligands. Using Xantphos as the ligand, β,γ-unsaturated esters are produced selectively in good yields. In contrast, the corresponding α,β-unsaturated esters are obtained with high regioselectivity in the presence of PPh2Py as the ligand. Preliminary mechanistic studies revealed that these two catalytic processes proceed by different reaction pathways. In addition, this novel protocol was successfully applied to convert an industrially available bulk chemical, 1,2-butadiene, into dimethyl adipate, which is a valuable feedstock for polymer and plasticizer syntheses, with high yield and TON (turnover number).
Photo-Promoted Decarboxylative Alkylation of α, β-Unsaturated Carboxylic Acids with ICH2CN for the Synthesis of β, γ-Unsaturated Nitriles
Pan, Chunxiang,Yang, Chunhui,Li, Kangkui,Zhang, Keyang,Zhu, Yuanbin,Wu, Shiyuan,Zhou, Yongyun,Fan, Baomin
, p. 7188 - 7193 (2021/10/01)
An efficient, catalyst/photocatalyst-free, and cost-effective methodology for the decarboxylative alkylation of α,β-unsaturated carboxylic acids to synthesize β,γ-unsaturated nitriles has been developed. The reaction proceeded in an environmentally benign atmosphere of blue light-emitting diode irradiation with K2CO3 and water at room temperature. The methodology worked for a wide range of substrates (22 examples) with up to 83% yield. The protocol is also compatible for gram-scale synthesis.
Preparation method of trans-4-phenyl-3-ethyl crotonate compound
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Paragraph 0028-0031, (2019/07/04)
The invention belongs to the technical field of pharmaceutical chemical intermediates and related chemistry, and relates to a preparation method of a trans-4-phenyl-3-ethyl crotonate compound. The preparation method comprises the following steps: using a
