451-40-1Relevant articles and documents
Hydration of Alkynes Catalyzed by L-Au-X under Solvent- and Acid-Free Conditions: New Insights into an Efficient, General, and Green Methodology
Gatto, Mattia,Del Zotto, Alessandro,Segato, Jacopo,Zuccaccia, Daniele
, p. 4685 - 4691 (2018)
L-Au-X [L = 1,3-bis(2,6-di-isopropylphenyl)-imidazol-2-ylidene {NHCiPr}, tris(3,5-bis(trifluoromethyl)phenyl)phosphine {PArF}, bis(imino)acenaphtene-1,3-bis(2,6-di-isopropylphenyl)dihydroimidazol-2-ylidene {BIAN}, 1,3-bis(2,6-di-isopropyl-phenyl)dihydroimidazol-2-ylidene {NHCCH2}, bis(tert-butylamino)methylidene {NAC}, 2-(di-tert-butylphosphino)biphenyl {JohnPhos}, tricyclohexylphosphine {PCy3}, triphenylphosphine {PPh3}, tris(2,4-di-tert-butylphenyl)phosphite {POR3}; X- = Cl-, OTf-, OTs-] catalysts were tested in the hydration of alkynes in neat and acid-free conditions. The overall catalytic evidence confirms that not only the counterion as previously observed by us but also the ligand play a crucial role. As a matter of fact, only complexes bearing NHC ligands showed appreciable catalytic activity. A complete rationalization of the ligand and counterion effects enabled us to develop a highly efficient methodology for the hydration of inactive diphenylacetylene in solvent-, silver-, and acid-free conditions. Thus, it was possible to reduce the catalyst loading to 0.01 mol % (with respect to diphenylacetylene) leading, to the best of our knowledge, to the highest TON (3400) and TOF (435 h-1) values found at 120 °C. The favorable catalytic conditions allowed us to reach for the first time very low E-factor (0.03) and high EMY (77) values for this substrate.
Reactivity and Crystal Structure of 10,11-Dihydro-10,11-epoxy-5H-dibenzocycloheptene. A Comparison with cis-Stilbene Oxide
Bellucci, Giuseppe,Chiappe, Cinzia,Marioni, F.,Spagna, Riccardo
, p. 2147 - 2151 (1990)
The kinetics and product distributions for the HClO4 catalysed hydrolysis of 10,11-dihydro-10,11-epoxy-5H-dibenzocycloheptene 1 and of cis-stilbene oxide 6 in tetrahydrofuran-water (8:2), have been investigated by HPLC.The former epoxide gives 9,10-dihydroanthracene-9-carbaldehyde 4 and the trans- and cis-10,11-dihydro-5H-dibenzocycloheptene-10,11-diols 2 and 3, in the ratio 6:6:1. cis-Stilbene oxide reacts with a rate constant ca. ten times lower, giving mostly (+/-)-1,2-diphenylethane-1,2-diol.These differences can be explained by the crystal structure of 1, which shows considerable ring strain due to the enlargement of the bond angles at C(10) and C(11).This structure also suggests an explanation for the much lower rate of the microsomal epoxide hydrolase catalysed hydration of 1 relative to 6.
Synthetic Methods and Reactions. 85. Reduction of α-Halo Ketones with Sodium Iodide/Chlorotrimethylsilane
Olah, George A.,Arvanaghi, Massoud,Vankar, Yashwant D.
, p. 3531 - 3532 (1980)
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Improving process efficiency of gold-catalyzed hydration of alkynes: Merging catalysis with membrane separation
A. C. A. Bayrakdar, Tahani,Nahra, Fady,Zugazua, Oihane,Eykens, Lies,Ormerod, Dominic,Nolan, Steven P.
, p. 2598 - 2604 (2020)
In this report, we investigate the integration of a membrane separation protocol in line with the gold-catalyzed hydration of alkynes. The catalytic reaction is optimised towards that end and subsequently merged with membrane technology via the development of an organic solvent nanofiltration (OSN) procedure. The protocol is investigated over both ceramic and polymeric membranes. Several gold catalysts were screened in the hydration of diphenylacetylene 1, and high rejection was observed in all cases using Borsig-type polymeric membranes. Catalyst recycling was also achieved up to 4 times using [Au(OTf)(IPr)] (3). In addition, the retained catalyst in the last catalytic cycle was analyzed and readily converted into [Au(Cl)(IPr)] (synthetic precursor to 3), using a straightforward treatment. The sustainability of the process was improved by using a green solvent, 2-methyltetrahydrofuran (Me-THF), and by reducing the amount of solvent used via the implementation of a second membrane.
Lanthanides in Organic Synthesis. 2. Reduction of α-Heterosubstituted Ketones
Molander, Gary A.,Hahn, Gregory
, p. 1135 - 1138 (1986)
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ABOUT THE MECHANISM OF THE PHOTOLYSIS OF BENZOYLTRIETHYLGERMANE, Et3GeCOPh
Taraban, M. B.,Maryasova, V. I.,Leshina, T. V.,Rybin, L. I.,Gendin, D. V.,Vyazankin, N. S.
, p. 347 - 356 (1987)
The detailed mechanism of the photolysis of benzoyltriethylgerman Et3GeCOPh in various media has been studied using the chemically induced dynamic nuclear polarization method (1 H CIDNP).It has been shown that in all cases the photolytic decomposition lea
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Blade-Font et al.
, p. 2646 (1960)
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Synthesis and characterization of gold(I) complexes of dibenzotropylidene-functionalized NHC ligands (Trop-NHCs)
Brill, Marcel,Collado, Alba,Cordes, David B.,Slawin, Alexandra M. Z.,Vogt, Matthias,Grützmacher, Hansj?rg,Nolan, Steven P.
, p. 263 - 274 (2015)
Gold(I) complexes of dibenzotropylidene-functionalized N-heterocyclic carbene ligands (Trop-NHCs) have been prepared in order to investigate their structural features and to reveal possible interactions of the olefin unit with the metal center. The precursor imidazolium chloride salts (R-1) were generated in a single step using N-substituted imidazoles (R = H, Me, DiPP, Ad) and 1 or 2 equiv of Trop-Cl, generating unsymmetrical and symmetrical NHC-olefin hybrids. The structural parameters of the ligands were determined by synthesis and X-ray diffraction analysis of their corresponding gold(I) chloride complexes, revealing highly flexible steric demands of the Trop unit. Conversion of these complexes with halide-abstracting reagents such as AgNTf2 and NaBArF24 cleanly gave neutral, NTf2-coordinated complexes of the type [(NHC)Au(NTf2)] (R-3) and the cationic bis-NHC-coordinated complexes [(NHC)2Au]BArF24 (R-4), respectively. The Gagosz-type complexes R-3 were further tested in the hydration of diphenylacetylene, showing a clear trend in activity depending on the ligand's sensitivity to hydrolysis.
Carbenoids by Deoxygenation of Carbonyl Compounds with Chloromethylsilanes
Smith, Clifford L.,Arnett, James,Ezike, James
, p. 653 - 654 (1980)
Deoxygenation of benzophenone, benzaldehyde, and cyclohexanone with chloromethylsilanes and zinc-copper couple in ether is reported to yield 2,2,2-triphenylacetophenone, a mixture of deoxybenzoin and diphenylacetaldehyde, and a bicyclic ketone with the proposed 2-oxocycloheptanespirocyclohexane structure, respectively; a carbene mechanism is proposed.
Reusable functionalized polysiloxane-supported palladium catalyst for Suzuki–Miyaura cross-coupling
Borkowski,Zawartka,Pospiech,Mizerska,Trzeciak,Cypryk,Tylus
, p. 270 - 277 (2011)
Palladium catalyst, obtained in the reaction of PdCl2(cod) with poly[(3-N-midazolopropyl)methylsiloxane-co-bisdimethylsiloxane], was used in the Suzuki–Miyaura cross-coupling of aryl bromides with phenylboronic acid. Catalytic reactions, performed at 40–80 °C in water or 2-propanol/water mixture, led to high yields of 2-methylbiphenyl with TOF up to 25,000 h?1. In recycling experiments, excellent results were obtained in eight subsequent runs. With application of microwave heating, more than 95% of product was formed under mild conditions and short time. XRD, TEM, and XPS methods evidenced the presence of Pd(0) nanoparticles bonded to the polysiloxane support. Their important role in the catalytic process was indicated by the results of mercury poisoning test.
Electrochemical oxidation-induced benzyl C–H carbonylation for the synthesis of aromatic α-diketones
Tan, Yu-Fang,Chen, Yuan,Li, Rui-Xue,Guan, Zhi,He, Yan-Hong
supporting information, (2021/12/21)
Electrochemical oxidation-induced direct carbonylation of benzyl C–H bond for the synthesis of aromatic α-diketones is described. In this process, tetrabutylammonium iodide (nBu4NI) not only acts as an electrolyte, but its iodine anion is oxidized to an iodine radical at the anode, acting as a hydrogen atom transfer agent. The iodine radical extracts the benzyl hydrogen atom and causes the carbonylation of the benzyl position, where O2 in the air is used as an oxygen source.
H2O2-mediated room temperature synthesis of 2-arylacetophenones from arylhydrazines and vinyl azides in water
Luo, Mengqiang,Zhang, Yaohong,Fang, Ping,Li, Yan,Qi, Chenze,Li, Yong,Shen, Runpu,Cheng, Kai,Wang, Hai
supporting information, p. 630 - 635 (2022/02/01)
An environmentally benign, cost-efficient and practical methodology for the room temperature synthesis of 2-arylacetophenones in water has been discovered. The facile and efficient transformation involves the oxidative radical addition of arylhydrazines with α-aryl vinyl azides in the presence of H2O2 (as a radical initiator) and PEG-800 (as a phase-transfer catalyst). From the viewpoint of green chemistry and organic synthesis, the present protocol is of great significance because of using cheap, non-toxic and readily available starting materials and reagents as well as amenability to gram-scale synthesis, which provides an attractive strategy to access 2-arylacetophenones.
Nonheme manganese(III) complexes for various olefin epoxidation: Synthesis, characterization and catalytic activity
Lee, Sojeong,Park, Soyoung,Lee, Myoung Mi,Lee, Jiyoung,Kim, Cheal
, (2021/03/14)
Three mononuclear imine-based non-heme manganese(III) complexes with tetradentate ligands which have two deprotonated phenolate moieties, ([(X2saloph)Mn(OAc)(H2O)], 1a for X = Cl, 1b for X = H, and 1c for X = CH3, saloph = N,N-o-phenylenebis(salicylidenaminato)), were synthesized and characterized by 1H NMR, 13C NMR, ESI-Mass and elemental analysis. MnIII complexes catalysed efficiently various olefin epoxidation reactions with meta-chloroperbenzoic acid (MCPBA) under the mild condition. MnIII complexes 1a and 1c with the electron-withdrawing group -Cl and electron-donating group –CH3 showed little substituent effect on the epoxidation reactions. Product analysis, Hammett study and competition experiments with cis- and trans-2-octene suggested that MnIV = O, MnV = O, and MnIII-OOC(O)R species might be key oxidants in the epoxidation reaction under this catalytic system. In addition, the use of PPAA as a mechanistic probe demonstrated that Mn-acylperoxo intermediate (MnIII-OOC(O)R) 2 generated from the reaction of peracid with manganese complexes underwent both the heterolysis and the homolysis to produce MnV = O (3) or MnIV = O species (4). Moreover, the MnIII-OOC(O)R 2 species could react directly with the easy-to-oxidize substrate to give epoxide, whereas the species 2 might not be competent to the difficult-to-oxidize substrate for the epoxidation reaction.
