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1.
M. Moghadam I. Mohammadpoor-Baltork S. Tangestaninejad V. Mirkhani L. Shariati M. Babaghanbari M. Zarea 《Journal of the Iranian Chemical Society》2009,6(4):789-799
A highly efficient method for the ring opening of epoxides catalyzed by ZrO(OTf)2 was adopted. This catalyst efficiently catalyzed alcoholysis, acetolysis and hydrolysis of epoxides and the corresponding alkoxy alcohols, acetoxy alcohols and 1,2- diols were obtained in excellent yields. Conversion of epoxides to 1,2-diacetetes, thiiranes and 1,3-dioxolanes was also performed in the presence of catalytic amounts of ZrO(OTf)2, and the corresponding products were obtained in high to excellent yields. The high catalytic activity of ZrO(OTf)2 is due to the replacement of Cl with OTf, which makes the ZrO(OTf)2 as efficient Lewis acid. 相似文献
2.
M. Moghadam S. Tangestaninejad V. Mirkhani I. Mohammadpoor-Baltork M. Babaghanbari M. Zarea L. Shariati S. A. Taghavi 《Journal of the Iranian Chemical Society》2009,6(3):523-532
Highly efficient acetylation and benzoylation of alcohols, phenols, amines and thiols with acetic and benzoic anhydrides catalyzed by new and reusable zirconyl triflate, ZrO(OTf)2, is reported. The high catalytic activity of electron deficient ZrO(OTf)2 can be used for the acetylation and benzoylation of not only primary alcohols but also sterically-hindered secondary and tertiary alcohols with acetic and benzoic anhydrides. Acetylation of phenols with acetic and benzoic anhydrides was achieved to afford the desired acetates and benzoates efficiently. This catalyst also efficiently catalyzed the acetylation and benzoylation of amines and thiols whereby the corresponding amides and thioesters were obtained in good to excellent yields. This catalyst can be reused several times without loss of its activity. 相似文献
3.
Clemens Taube Dr. Kai Schwedtmann Medena Noikham Prof. Dr. Ekasith Somsook Dr. Felix Hennersdorf Prof. Dr. Robert Wolf Prof. Dr. Jan J. Weigand 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(9):3613-3619
[LCRP((PhP)2C2H4)][OTf] ( 4 a,b [OTf]) and [LCiPrP(PPh2)2][OTf] ( 5 b [OTf]) were prepared from the reaction of imidazoliumyl-substituted dipyrazolylphosphane triflate salts [LCRP(pyr)2][OTf] ( 3 a,b [OTf]; a : R=Me, b =iPr; LCR=1,3-dialkyl-4,5-dimethylimidazol-2-yl; pyr=3,5-dimethylpyrazol-1-yl) with the secondary phosphanes PhP(H)C2H4P(H)Ph) and Ph2PH. A stepwise double P−N/P−P bond metathesis to catena-tetraphosphane-2,3-diium triflate salt [(Ph2P)2(LCMeP)2][OTf]2 ( 7 a [OTf]2) is observed when reacting 3 a [OTf] with diphosphane P2Ph4. The coordination ability of 5 b [OTf] was probed with selected coinage metal salts [Cu(CH3CN)4]OTf, AgOTf and AuCl(tht) (tht=tetrahydrothiophene). For AuCl(tht), the helical complex [{(Ph2PPLCiPr)Au}4][OTf]4 ( 9 [OTf]4) was unexpectedly formed as a result of a chloride-induced P−P bond cleavage. The weakly coordinating triflate anion enables the formation of the expected copper(I) and silver(I) complexes [( 5 b )M(CH3CN)3][OTf]2 (M=Cu, Ag) ( 10 [OTf]2, 11 [OTf]2). 相似文献
4.
Clemens Taube Kai Schwedtmann Medena Noikham Ekasith Somsook Felix Hennersdorf Robert Wolf Jan J. Weigand 《Angewandte Chemie (International ed. in English)》2020,59(9):3585-3591
[LCRP((PhP)2C2H4)][OTf] ( 4 a,b [OTf]) and [LCiPrP(PPh2)2][OTf] ( 5 b [OTf]) were prepared from the reaction of imidazoliumyl‐substituted dipyrazolylphosphane triflate salts [LCRP(pyr)2][OTf] ( 3 a,b [OTf]; a : R=Me, b =iPr; LCR=1,3‐dialkyl‐4,5‐dimethylimidazol‐2‐yl; pyr=3,5‐dimethylpyrazol‐1‐yl) with the secondary phosphanes PhP(H)C2H4P(H)Ph) and Ph2PH. A stepwise double P?N/P?P bond metathesis to catena‐tetraphosphane‐2,3‐diium triflate salt [(Ph2P)2(LCMeP)2][OTf]2 ( 7 a [OTf]2) is observed when reacting 3 a [OTf] with diphosphane P2Ph4. The coordination ability of 5 b [OTf] was probed with selected coinage metal salts [Cu(CH3CN)4]OTf, AgOTf and AuCl(tht) (tht=tetrahydrothiophene). For AuCl(tht), the helical complex [{(Ph2PPLCiPr)Au}4][OTf]4 ( 9 [OTf]4) was unexpectedly formed as a result of a chloride‐induced P?P bond cleavage. The weakly coordinating triflate anion enables the formation of the expected copper(I) and silver(I) complexes [( 5 b )M(CH3CN)3][OTf]2 (M=Cu, Ag) ( 10 [OTf]2, 11 [OTf]2). 相似文献
5.
《Tetrahedron: Asymmetry》2007,18(9):1129-1133
Chiral Schiff-bases prepared from chiral amino alcohols catalyze the enantioselective Henry (nitro aldol) reaction between nitromethane and p-nitrobenzaldehyde in the presence of Cu(OTf)2 and Zn(OTf)2. Zn(OTf)2 promoted the reaction yield, while Cu(OTf)2 promoted the enantiomeric excess. The highest enantioselectivities were observed with ligand 3 (44% ee) and ligand 5 (47% ee). 相似文献
6.
Stefan Schaub Andreas Miska Dr. Jonathan Becker Dr. Stefan Zahn Prof. Dr. Doreen Mollenhauer Dr. Sadashivaiah Sakshath Prof. Dr. Volker Schünemann Prof. Dr. Siegfried Schindler 《Angewandte Chemie (International ed. in English)》2018,57(19):5355-5358
The iron(IV) oxido complex [(tmc)Fe=O(OTf)]OTf with the macrocyclic ligand 1,4,8,11‐tetramethyl‐1,4,8,11‐tetraazacyclo‐tetradecane (tmc) has been synthesized using ozone as an oxidant. By adding water to this compound the complex [(H2O)(tmc)Fe=O)](OTf)2 could be prepared. This complex is important in regard to a better understanding of the reactivity of FeIV oxido complexes. Mössbauer measurements using the solid compound showed an isomer shift of δ=0.19 mm s?1 and a quadrupole splitting ΔEQ=1.38 mm s?1, confirming the high‐valent FeIV state. DFT calculations were performed and led to an assignment of triplet spin multiplicity. Crystallographic characterization of [(H2O)(tmc)Fe=O)](OTf)2 as well as of starting materials [(tmc)Fe(CH3CN)](OTf)2 and [(tmc)Fe(OTf)]OTf together with previous results strongly suggest that [(H2O)(tmc)Fe=O)](OTf)2 was formed similar to the oxido–hydroxido tautomerism analogous to heme systems. 相似文献
7.
Establishing the Coordination Chemistry of Antimony(V) Cations: Systematic Assessment of Ph4Sb(OTf) and Ph3Sb(OTf)2 as Lewis Acceptors
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Dr. Alasdair P. M. Robertson Saurabh S. Chitnis Dr. Hilary A. Jenkins Dr. Robert McDonald Dr. Michael J. Ferguson Prof. Neil Burford 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(21):7902-7913
The coordination chemistry of the stiboranes Ph4Sb(OTf) ( 1 a , OTf = OSO2CF3) and Ph3Sb(OTf)2 ( 3 ) with Lewis bases has been investigated. The significant steric encumbrance of the Sb center in 1 a precludes interaction with most ligands, but the relatively low steric demands of 4‐methylpyridine‐N‐oxide (OPyrMe) and OPMe3 enabled the characterization of [Ph4Sb(OPyrMe)][OTf] ( 2 a ) and [Ph4Sb(OPMe3)][OTf] ( 2 b ), rare examples of structurally characterized complexes of stibonium acceptors. In contrast, 3 was found to engage a variety of Lewis bases, forming stable isolable complexes of the form [Ph3Sb(donor)2][OTf]2 [donor=OPMe3 ( 6 a ), OPCy3 ( 6 b , Cy=cyclohexyl), OPPh3 ( 6 c ), OPyrMe ( 6 d )], [Ph3Sb(dmap)2(OTf)][OTf] ( 6 e , dmap=4‐(dimethylamino)pyridine) and [Ph3Sb(donor)(OTf)][OTf] [donor=1,10‐phenanthroline ( 7 a ) or 2,2′‐bipy ( 7 b , bipy=bipyridine)]. These compounds exhibit significant structural diversity in the solid‐state, and undergo ligand exchange reactions in line with their assignment as coordination complexes. Compound 3 did not form stable complexes with phosphine donors, with reactions instead leading to redox processes yielding SbPh3 and products of phosphine oxidation. 相似文献
8.
《Comptes Rendus Chimie》2002,5(2):81-87
Uranium triflate complexes. We review here the different preparations of uranium triflates that we have developed in the course of these last years in our laboratory. Protonation of 〚U〛–R and 〚U〛–NR2 (R = alkyl) bonds with pyridinium triflate constitutes a general and efficient route towards triflate complexes. This method is very suitable for the preparation of organometallic compounds such as U(Cp)3(OTf), U(Cp)2(OTf)2(py), U(Cp*)2(OTf)2, and U(Cot)(OTf)2(py), which have been crystallographically characterised. The homoleptic species U(OTf)n (n = 3, 4) are easily prepared by heating a mixture of uranium turnings or UH3 in triflic acid. By adjusting the temperature to 120 or 180 °C, either U(OTf)3 or U(OTf)4 is isolated. Treatment of UO3 with pure or aqueous solution of triflic acid leads to the non-solvated uranyl triflate UO2(OTf)2, which is more conveniently obtained by heating a suspension of UO3 in triflic anhydride. This reactant is an excellent dehydrating agent and enables the preparation of UO2(OTf)2 and Ce(OTf)4 from the hydrated starting materials. 相似文献
9.
Yutaka Isobe Tamaki Nakano Yoshio Okamoto 《Journal of polymer science. Part A, Polymer chemistry》2001,39(9):1463-1471
The free‐radical polymerizations of methyl methacrylate (MMA), ethyl methacrylate, isopropyl methacrylate, and 2‐methoxyethyl methacrylate were carried out in the presence of various Lewis acids. The MMA polymerization in the presence of scandium trifluoromethanesulfonate [Sc(OTf)3] in toluene or CHCl3 produced a polymer with a higher isotacticity and heterotacticity than that produced in the absence of Sc(OTf)3. Similar effects were observed during the polymerization of the other monomers. ScCl3, Yb(OTf)3, Er(OTf)3, HfCl4, HfBr4, and In(OTf)3 also increased the isotacticity and heterotacticity of the polymers. The effects of the Lewis acids were greater in a solvent with a lower polarity and were negligible in tetrahydrofuran and N,N‐dimethylformamide. Sc(OTf)3 was also found to accelerate the polymerization of MMA. On the basis of an NMR analysis of a mixture of Sc(OTf)3, MMA, and poly(methyl methacrylate), the monomer–Sc(OTf)3 interaction seems to be involved in the stereochemical mechanism of the polymerization. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1463–1471, 2001 相似文献
10.
《Journal of Energy Chemistry》2014,23(1):97-104
Acidic ionic liquid ([BsAIm][OTf]) was immobilized on sulfhydryl-group-modified SiO2 (MPS-SiO2) via free radical addition reaction. The [BsAIm][OTf] loading on acidic ionic liquid-functionalized silica ([BsAIm][OTf]/SiO2) was controlled through tuning the sulfydryl (SH) content of MPS-SiO2. All the samples were characterized by FT-IR, elemental analysis, N2 adsorption-desorption measurements and TG-DTA. The catalytic performance of [BsAIm][OTf]/SiO2 in the esterification of oleic acid and the transesterification of glycerol trioleate for biodiesel production was investigated. The results showed that with the increase of [BsAIm][OTf] loading on SiO2 the specific surface area and pore volume of [BsAIm][OTf]/SiO2 decreased, and the pore diameter of [BsAIm][OTf]/SiO2 narrowed. In the esterificaiton of oleic acid, the oleic acid conversion increased with the increasing [BsAIm][OTf] loading. In the transesterification of glycerol trioleate, with the increasing [BsAIm][OTf] loading the glycerol trioleate conversion decreased and the selectivities to glycerol monooleate and methyl oleate increased. 相似文献
11.
Shū Kobayashi Ryoji HirabayashiHaruka Shimizu Haruro IshitaniYasuhiro Yamashita 《Tetrahedron letters》2003,44(16):3351-3354
[3+2] Cycloaddition between hydrazones and olefins was accelerated in the presence of a stoichiometric amount of BF3·OEt2 or a catalytic amount of Zr(OTf)4, Hf(OTf)4, or Sc(OTf)3 under mild conditions. The corresponding pyrazolidine derivatives were obtained in moderate to high yields using this novel [3+2] Lewis acid catalysis. 相似文献
12.
A. A. Turmasova E. S. Spesivaya Dzh. N. Konshina V. V. Konshin 《Russian Chemical Bulletin》2012,61(9):1733-1735
Reactions of adamantan-1-ol with β-dicarbonyl compounds in 1,2-dichloroethane in the presence of In(OTf)3, Ga(OTf)3, Sc(OTf)3, or Cu(OTf)2 give the corresponding adamantylated derivatives in 45–93% yields. 相似文献
13.
Some new oxozirconium(IV) complexes: ZrO(An)2, ZrO(Gly)2, ZrO(HSal)2, ZrO(HPth)2, ZrO(Pic)2(HPic)2, and ZrO(Quin)2(H Quin)2 have been isolated from the reactions of ZrO(CH3COO)2CH3COOH with anthranilic acid (HAn), glycine (HGly), salicylic acid (H2Sal), phthalic acid (H2Pth), picolinic acid (HPic), and 8-quinolinol (HQuin) respectively. Their important infrared bands and wherever possible molar conductance and molecular weight have been reported. 相似文献
14.
Subvalent Gallium Triflates – Potentially Useful Starting Materials for Gallium Cluster Compounds By reaction of GaCp* with trifluormethanesulfonic acid in hexane a mixture of gallium trifluormethanesulfonates (triflates, OTf) is obtained. This mixture reacts readily with lithiumsilanides [Li(thf)3Si(SiMe3)2R] (R = Me, SiMe3) to afford the cluster compounds [Ga6{Si(SiMe3)Me}6], [Ga2{Si(SiMe3)3}4] and [Ga10{Si(SiMe3)3}6]. By crystallization from various solvents the gallium triflates [Ga(OTf)3(thf)3], [HGa(OTf)(thf)4]+ [Ga(OTf)4(thf)3]−, [Cp*GaGa(OTf)2]2 and [Ga(toluene)2]+ [Ga5(OTf)6(Cp*)2]− were isolated and characterized by single crystal X ray structure analysis. 相似文献
15.
Dr. Dirk Hollmann Dr. Kathleen Grabow Dr. Haijun Jiao Dr. Monty Kessler Dr. Anke Spannenberg Dr. Torsten Beweries Dr. Ursula Bentrup Prof. Angelika Brückner 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(41):13705-13713
A detailed mechanism of hydrogen production by reduction of water with decamethyltitanocene triflate [Cp*2TiIII(OTf)] has been derived for the first time, based on a comprehensive in situ spectroscopic study including EPR and ATR‐FTIR spectroscopy supported by DFT calculations. It is demonstrated that two H2O molecules coordinate to [Cp*2TiIII(OTf)] subsequently forming [Cp2*TiIII(H2O)(OTf)] and [Cp*TiIII(H2O)2(OTf)]. Triflate stabilizes the water ligands by hydrogen bonding. Liberation of hydrogen proceeds only from the diaqua complex [Cp*TiIII(H2O)2(OTf)] and involves, most probably, abstraction and recombination of two H atoms from two molecules of [Cp*TiIII(H2O)2(OTf)] in close vicinity, which is driven by the formation of a strong covalent Ti? OH bond in the resulting final product [Cp*2TiIV(OTf)(OH)]. 相似文献
16.
Dr. Clemens Taube Jannis Fidelius Dr. Kai Schwedtmann Dr. Christopher Ziegler Florian Kreuter Dr. Leigh Loots Prof. Dr. Leonard J. Barbour Prof. Dr. Ralf Tonner-Zech Prof. Dr. Robert Wolf Prof. Dr. Jan J. Weigand 《Angewandte Chemie (International ed. in English)》2023,62(47):e202306706
Although diphosphene transition metal complexes are known to undergo E to Z isomerization upon irradiation with UV light, their potential for photoswitching has remained poorly explored. In this study, we present diphosphene complexes capable of reversible photoisomerizations through haptotropic rearrangements. The compounds [( 2 -κ2P,κ6C)Mo(CO)2][OTf] ( 3 a [OTf]), [( 2 -κ2P,κ6C)Fe(CO)][OTf] ( 3 b [OTf]), and [( 2 -κ2P)Fe(CO)4][OTf] ( 4 [OTf]) were prepared using the triflate salt [(LC)P=P(Dipp)][OTf] ( 2 [OTf) as a precursor (LC=4,5-dichloro-1,3-bis(2,6-diisiopropylphenyl)-imidazolin-2-yl; Dipp=2,6-diisiopropylphenyl, OTf=triflate). Upon exposure to blue or UV light (λ=400 nm, 470 nm), the initially red-colored η2-diphosphene complexes 3 a , b [OTf] readily undergo isomerization to form blue-colored η1-complexes [( 2 -κ1P,κ6C)M(CO)n][OTf] ( 5 a , b [OTf]; a : M=Mo, n=2; b : M=Fe, n=1). This haptotropic rearrangement is reversible, and the (κ2P,κ6C)-coordination mode gradually reverts back upon dissolution in coordinating solvents or more rapidly upon exposure to yellow or red irradiation (λ=590 nm, 630 nm). The electronic reasons for the reversible visible-light-induced photoswitching observed for 3 a , b [OTf] are elucidated by DFT calculations. These calculations indicate that the photochromic isomerization originates from the S1 excited state and proceeds through a conical intersection. 相似文献
17.
Reaction of 2-formylbenzoates with hexamethyldisilazane and diethyl phosphite in the presence of Yb(OTf)3 proceeded smoothly at room temperature to afford addition adducts, which were readily cyclized to 3-phosphonate phthalides by adding trifluoroacetic acid (TFA). The reactions employing Sc(OTf)3 instead of Yb(OTf)3 produced 3-phosphonate isoindolinones without addition of TFA. 相似文献
18.
The ring-opening polymerizations (ROPs) of lactones catalyzed by rare-earth metal trifluoromethanesulfonates (triflates) (RE(OTf)3) were examined. Among various complexes, scandium triflate (Sc(OTf)3) emerged as an effective catalyst in toluene. The ROP of lactones by Sc(OTf)3 proceeded in a living fashion, and the number of polymer molecules was controlled by the amount of protic additives such as benzyl alcohol and H2O. In other words, one molecule of Sc(OTf)3 catalytically produced a number of polymer molecules (up to 40 molecules) depending on the amount of protic additives. The plausible mechanism was depicted as an activated monomer mechanism. The polylactones with a number-average molecular weight over 25,000 were successfully synthesized. Immobilization of RE(OTf)3 was investigated in three ionic liquids, and cerium triflate (Ce(OTf)4) showed relatively high catalytic activity in a biphasic system of 1-butyl-3-methylimidazolium hexafluoroantimonate and toluene in the ROP of ?-caprolactone (CL). The ionic liquid containing Ce(OTf)4 was used, at least three times, in the ROP of CL without losing catalytic activity. 相似文献
19.
Santosh Kumar Giri Monika Verma K. P. Ravindranathan Kartha 《Journal of carbohydrate chemistry》2013,32(8-9):464-478
Indium(III) trifluoromethanesulfonate has been found to be extremely efficient in catalyzing acyl transfer reactions of various carbohydrates and their derivatives. Selective acetolyses of certain benzyl ethers/isopropylidene acetals of sugars have been possible using In(OTf)3 in Ac2O (neat). Reaction of the per-O-acetate of 2-deoxy-2-phthalimido-D-glucose with benzyl mercaptan in the presence of In(OTf)3 led to the formation of the corresponding thioglycoside in high yield. Facile formation and hydrolysis of the isopropylidene and benzylidene acetals of various carbohydrates have also been achieved very efficiently in the presence of In(OTf)3. The results show great promise for In(OTf)3 in synthetic carbohydrate chemistry. 相似文献
20.
Sarah A. Weicker Prof. Dr. Douglas W. Stephan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(37):13027-13034
Silyl triflates of the form R4?nSi(OTf)n (n=1, 2; OTf=OSO3CF3) are shown to activate carbon dioxide when paired with bulky alkyl‐substituted Group 15 bases. Combinations of silyl triflates and 2,2,6,6‐tetramethylpiperidine react with CO2 to afford silyl carbamates via a frustrated Lewis pair‐type mechanism. With trialkylphosphines, the silyl triflates R3Si(OTf) reversibly bind CO2 affording [R′3P(CO2)SiR3][OTf] whereas when Ph2Si(OTf)2 is used one or two molecules of CO2 can be sequestered. The latter bis‐CO2 product is favoured at low temperatures and by excess phosphine. 相似文献