- A stable and porous iridium(III)-porphyrin metal-organic framework: Synthesis, structure and catalysis
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Self-assembly of a new metalloporphyrin tetracarboxylic ligand Ir(TCPP)Cl (TCPP = tetrakis(4-carboxyphenyl)porphyrin) with ZrCl4 in the presence of benzoic acid leads to the formation of a three-dimensional (3D) iridium(III)-porphyrin metal-organic framework (Ir-PMOF) with the formula of [(Zr6(μ3-O)8(OH)2(H2O)10)2(Ir(TCPP)Cl)3]·solvents (Ir-PMOF-1(Zr)), which possesses square-shaped channels of 1.9 × 1.9 nm2 (atom-to-atom distances across opposite Ir metal atoms) in three orthogonal directions as disclosed by the single-crystal X-ray diffraction analysis. Ir-PMOF-1(Zr) represents the first MOF bearing a self-supporting iridium-porphyrin catalytic framework, featuring high porosity and stability. The catalytic tests disclose that the activated Ir-PMOF-1(Zr) can promote O-H insertion with a turnover frequency (TOF) up to 4260 h-1. Ir-PMOF-1(Zr) can be recycled and reused for 10 runs without significant loss of catalytic activity, and the total turnover number (TON) for O-H insertion after 10 successive runs reaches 875.
- Cui, Hao,Wang, Yingxia,Wang, Yanhu,Fan, Yan-Zhong,Zhang, Li,Su, Cheng-Yong
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p. 2203 - 2209
(2016/03/30)
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- N-Heterocyclic Carbene-Phosphinidene Complexes of the Coinage Metals
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Coinage metal complexes of the N-heterocyclic carbene-phosphinidene adduct IPr·PPh (IPr=1,3-bis(2,6-diisopropylphenyl)imidazolin-2-ylidene) were prepared by its reaction with CuCl, AgCl, and [(Me2S)AuCl], which afforded the monometallic complexes [(IPr·PPh)MCl] (M=Cu, Ag, Au). The reaction with two equivalents of the metal halides gave bimetallic [(IPr·PPh)(MCl)2] (M=Cu, Au); the corresponding disilver complex could not be isolated. [(IPr·PPh)(CuOTf)2] was prepared by reaction with copper(I) trifluoromethanesulfonate. Treatment of [(IPr·PPh)(MCl)2] (M=Cu, Au) with Na(BArF) or AgSbF6 afforded the tetranuclear complexes [(IPr·PPh)2M4Cl2]X2 (X=BArF or SbF6), which contain unusual eight-membered M4Cl2P2 rings with short cuprophilic or aurophilic contacts along the chlorine-bridged M...M axes. Complete chloride abstraction from [(IPr·PPh)(AuCl)2] was achieved with two equivalents of AgSbF6 in the presence of tetrahydrothiophene (THT) to form [(IPr·PPh){Au(THT)}2][SbF6]2. The cationic tetra- and dinuclear complexes were used as catalysts for enyne cyclization and carbene transfer reactions.
- Doddi, Adinarayana,Bockfeld, Dirk,Nasr, Alexandre,Bannenberg, Thomas,Jones, Peter G.,Tamm, Matthias
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p. 16178 - 16189
(2015/11/03)
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- Efficient and catalyst-free condensation of acid chlorides and alcohols using continuous flow
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An efficient, catalyst-free continuous flow procedure for the condensation of acid chlorides and alcohols was developed. Different esters could be obtained using this protocol with excellent conversions starting from the corresponding acid chlorides and alcohols in very short reaction times (5-7 min). The reaction was performed solventless for liquid reagents but requires a solvent for solid reagents in order to prevent clogging of the microreactor. Since no catalyst is needed, the purification of the reaction mixture is very straightforward. Scale-up of the reaction to a microreactor with an internal volume of 13.8 ml makes it possible to produce 2.2 g min-1 of ester with an isolated yield of 98% and recuperation of the formed HCl.
- Van Waes, Frederik E. A.,Cukalovic, A.,Stevens, Christian V.,Drabowicz, J.
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p. 2776 - 2779,4
(2020/09/14)
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- Combinatorial synthesis of 3,5-Dimethylene substituted 1,2,4-Triazoles
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Combinatorial cyclizations of imidates and hydrazides with methylene linked R groups, generated from the corresponding nitriles and carboxylic acids, respectively, provided a large library of 3,5-dimethylene substituted 1,2,4- trizoles. 2011 Bentham Science Publishers Ltd.
- Woodard, Scott S.,Jerome, Kevin D.
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experimental part
p. 132 - 137
(2012/04/18)
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- InCl3 catalyzed carbene insertion into O-H bonds: Efficient synthesis of ethers
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An efficient InCl3 mediated insertion of the carbene fragment (:CHCO2Et), generated in situ from ethyl diazoacetate into O-H bond of a series of saturated and unsaturated alcohols under mild conditions has been developed to afford the corresponding ethers as exclusive products in good to high yields (70-95%) and in shorter reaction times. In the case of unsaturated alcohols, the reaction proceeded with unprecedented selectivity resulting in ethers as the only products and in high yields.
- Radha Krishna, Palakodety,Prapurna, Y. Lakshmi,Alivelu, Munagala
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experimental part
p. 3460 - 3462
(2011/06/27)
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- Gold(i) "click" 1,2,3-triazolylidenes: Synthesis, self-assembly and catalysis
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Novel gold(i) "click" carbene(1,2,3-triazolylidene) complexes have been synthesised, characterised and exploited for the self-assembly of a metallomacrocycle and as precatalysts for gold(i)-catalysed reactions.
- Kilpin, Kelly J.,Paul, Ursula S. D.,Lee, Ai-Lan,Crowley, James D.
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supporting information; experimental part
p. 328 - 330
(2011/03/17)
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- Site-directed anchoring of an N-heterocyclic carbene on a dimetal platform: Evaluation of a pair of diruthenium(i) catalysts for carbene-transfer reactions from ethyl diazoacetate
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Site-directed anchoring of naphthyridine-functionalized N-heterocylic carbene (NHC) is achieved on a metal-metal singly bonded diruthenium(I) platform. Room-temperature treatment of 1-isopropyl-3-(5,7-dimethyl-1,8- naphthyrid-2-yl)imidazolium bromide (PINA·HBr) with Ru 2(CH3COO)2(CO)4 in acetonitrile affords the unsupported compound Ru2(CO) 4(μ2C2,N1-PIN)2Br 2 (1). Judicious alteration in the NHC ligand resulted in the bridged compound Ru2(CO)4(CH3COO)(μ2- μ2C2,N1-BIN)Br (2) (BIN = 1-benzyl-3-(3-phenyl-1,8-naphthyrid-2-yl)imidazol-2-ylidene). X-ray analysis revealed the chelate binding of PIN on each ruthenium at equatorial sites for 1, and the bridge-chelate binding of BIN spanning the diruthenium core for 2. The catalytic utilities of the BArF (tetrakis(3,5-bis(trifluoromethyl) phenyl)borate) salts of these compounds are evaluated toward carbene-transfer reactions from ethyl diazoacetate including aldehyde olefination, cyclopropanation, and X-H (X = O, N) insertions. 1-BArF is clearly shown to be the superior catalyst. DFT calculations are undertaken to understand the influence of NHC binding on the electronic structures of the "Ru 2(CO)4" core and to rationalize the lower activity of 2-BArF.
- Saha, Biswajit,Ghatak, Tapas,Sinha, Arup,Rahaman, S. M. Wahidur,Bera, Jitendra K.
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scheme or table
p. 2051 - 2058
(2011/06/18)
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- A RuII-N-heterocyclic carbene (NHC) complex from metal-metal singly bonded diruthenium(I) precursor: Synthesis, structure and catalytic evaluation
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A mononuclear Ru(II)-N-heterocyclic carbene (NHC) complex [Ru II(CO)2(κ2C,N-BIN)(H2O)Br] [OTf] (OTf = trifluoromethane sulphonate) (1) has been synthesized in high-yield by the oxidative cleavage of the metal-metal singly-bonded diruthenium(I) precursor [Ru2(CO)4(CH3CN)6(OTf) 2] with 1,8-naphthyridine functionalized NHC precursor 1-benzyl-3-(5,7-dimethyl-1,8-naphthyrid-2-yl)imidazolium bromide (BIN·HBr) at room temperature. Compound 1 catalyzes transfer hydrogenation of ketones to alcohols, and carbene-transfer from ethyl diazoacetate to a variety of substrates. It is shown to be an excellent catalyst for the insertion of carbene into the O-H and N-H bonds of alcohols and amines.
- Sinha, Arup,Daw, Prosenjit,Rahaman, S.M. Wahidur,Saha, Biswajit,Bera, Jitendra K.
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experimental part
p. 1248 - 1257
(2011/04/22)
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- PROCESS FOR PRODUCING ESTER COMPOUND
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PROBLEM To provide an environmentally-friendly method for producing industrially an ester compound. SOLUTION The present invention is a method for producing an ester compound which comprises subjecting a carboxylic acid and an alcohol to dehydration-condensation reaction using an involatile acid catalyst and then removing the residual acid catalyst by bringing a weak basic substance into contact with the residual acid catalyst.
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Page/Page column 16
(2010/12/31)
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- Synthesis of new copper(i) complexes with tris(2-pyridyl) ligands. Applications to carbene and nitrene transfer reactions
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New copper(i) complexes with tris(2-pyridyl)methane (TPC), tris(2-pyridyl)methoxymethane (TPM) and tris(2-pyridyl)amine (TPN) ligands have been synthesized and characterized, including structural determinations by X-ray diffraction of some examples. Their activity as catalysts in carbene and nitrene transfer reactions was studied.
- Perez, Julio,Morales, Dolores,Garcia-Escudero, Luis A.,Martinez-Garcia, Hector,Miguel, Daniel,Bernad, Pablo
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scheme or table
p. 375 - 382
(2009/04/14)
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- Synthesis, isolation and characterization of cationic gold(I) N-heterocyclic carbene (NHC) complexes
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A number of cationic gold(I) complexes have been synthesized and found to be stabilized by the use of N-heterocyclic carbene ligands. These species are often employed as in situ-generated reactive intermediates in gold catalyzed organic transformations. An isolated, well-defined species was tested in gold-mediated carbene transfer reactions from ethyl diazoacetate. The Royal Society of Chemistry 2006.
- De Fremont, Pierre,Stevens, Edwin D.,Fructos, Manuel R.,Mar Diaz-Requejo,Perez, Pedro J.,Nolan, Steven P.
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p. 2045 - 2047
(2008/09/18)
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- A gold catalyst for carbene-transfer reactions from ethyl diazoacetate
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(Chemical Equation Presented) Approaching El Dorado: A gold catalyst has been discovered that transfers a carbene unit from ethyl diazoacetate to aromatic substrates (see scheme) as well as olefins, amines, and alcohols. The insertion of carbene units into the C-H bonds of the aromatic ring of benzene, toluene, and styrene is a novel reaction. R = H, CH3, CH=CH 2; IPr = 1,3-bis(diisopropylphenyl)imidazol-2-ylidene.
- Fructos, Manuel R.,Belderrain, Tomas R.,De Fremont, Pierre,Scott, Natalie M.,Nolan, Steven P.,Diaz-Requejo, M Mar,Perez, Pedro J.
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p. 5284 - 5288
(2007/10/03)
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- Catalytic transformations of diazo compounds promoted by platinum(0) and dicationic platinum(II) complexes
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9-Diazofluorene (DAF) is decomposed either stoichiometrically or catalytically in the presence of the platinum(0) complex [Pt(C2H4)(PPh3)2] to give difluoren-9-ylidene-hydrazine in high yield. Under analogous reaction conditions, diphenyldiazomethane gives mostly the azine, Ph2CNNCPh2, while ethyl diazoacetate (EDA) affords, in low yield, a mixture of diethyl fumarate and maleate in approximately 10:1 molar ratio. The cyclopropanation of styrene with EDA is catalyzed by a series of dicationic complexes of the type [PtL2(NCCH3)2][Y]2 (L2=2PPh3, Ph2PCH=CHPPh2, Ph2PCH2CH2PPh2; Y=BF4, CF3SO3) in 1,2-dichloroethane at 60 °C for 24 h. DAF and EDA undergo insertion reactions into the OH bond of alcohols ROH (R=Me, Et, t-Bu, CH2CHCH2, Ph) at 25 °C in CH2Cl2-ROH (DAF or EDA-ROH molar ratio 1/20) in the presence of 1% mol of several dicationic platinum(II) complexes to give the corresponding ethers in excellent yields.
- Bertani, Roberta,Biasiolo, Monica,Darini, Katia,Michelin, Rino A,Mozzon, Mirto,Visentin, Fabiano,Zanotto, Livio
-
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- Ruthenium complexes containing diamine-based ligands as catalysts for insertion of carbenes into O-H bonds of alcohols
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Ruthenium complexes with N-(p-toluenesulfonyl)-diamine ligands are efficient catalysts for insertion of carbenes generated from diazo compounds into O-H bonds of alcohols.
- Simal, Francois,Demonceau, Albert,Noels, Alfred F.
-
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- Insertion of carbenes into O-H bonds of alcohols catalysed by platinum complexes
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The addition of diazoesters to alcohols in the presence of a catalytic amount of platinum complexes provides the corresponding O-H insertion products in good to excellent yields.
- Schils, Raphael,Simal, Francois,Demonceau, Albert,Noels, Alfred F.,Eremenko, Igor L.,Sidorov, Aleksei A.,Nefedov, Sergei E.
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p. 7849 - 7852
(2007/10/03)
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- Organic reactions catalyzed by methylrhenium trioxide: Reactions of ethyl diazoacetate and organic azides
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Methylrhenium trioxide (CH3ReO3 or MTO) catalyzes several classes of reactions of ethyl diazoacetate, EDA. It is the first high valent oxo complex for carbene transfer. Under mild conditions and in the absence of other substrates, EDA was converted to a 9:1 mixture of diethyl maleate and diethyl fumarate. In the presence of alcohols, α-alkoxy ethyl acetates were obtained in good yield. The yields dropped for the larger and more branched alcohols, the balance of material being diethyl maleate and fumarate. An electron-donating group in the para position of phenols favors the formation of α-phenoxy ethyl acetates. The use of EDA to form α-thio ethyl acetates and N-substituted glycine ethyl esters, on the other hand, is hardly affected by the size or structure of the parent thiol or amine, with all of these reactions proceeding in high yield. MTO-catalyzed cycloaddition reactions occur between EDA and aromatic imines, olefins, and carbonyl compounds. Three-membered ring products are formed: aziridines, cyclopropanes, and epoxides, respectively. The reactions favor the formation of trans products, and provide a convenient route for the preparation of aziridines. Intermediate carbenoid and nitrenoid species have been proposed. In the presence of an oxygen source such as an epoxide, ethyl diazoacetate and azibenzil are converted to an oxalic acid monoethyl ester and tobenzil; at the same time the epoxide was converted to an olefin. These results provide further support for the proposed intermediate, a cyclic species containing Re, O, and CHCO2Et (or, occasionally, CPhC(O)Ph)in a three-membered ring.
- Zhu, Zuolin,Espenson, James H.
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p. 9901 - 9907
(2007/10/03)
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- Reactions of Carbenes with Oxetane and with Oxetane/ Methanol Mixtures
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Ethoxycarbonylcarbene, bis(methoxycarbonyl)carbene, phenylcarbene (17a), diphenylcarbene (17b), fluorenylidene (17c), 2-furylcarbene (31a), 2-furyl(phenyl)carbene (31b), 4-oxo-2,5-cyclohexadienylidene (40), and 4,4-dimethyl-2,5-cyclohexadienylidene (53) were generated by photolysis of the appropriate diazo compounds.With neat oxetane, most of these carbenes react by competitive C-H insertion (B -> A, Scheme 1) and ylide formation (B -> C). 31a and 40 do not insert into C-H bonds; 31b does not attack oxetane but rearranges exclusively with formation of 26.The ylides undergo Stevens rearrangement to give tetrahydrofurans (C -> D) and α',β-elimination, leading to allyl ethers (C -> E).With oxetane/ methanol mixtures, the intervention of oxonium ions (H) is indicated by the formation of 1,3-dialkoxypropanes (I).The oxonium ions arise either by protonation of the ylides (C -> H) or by protonation of the carbenes (B -> G), followed by electrophilic attack of the carbocations (G) at oxetane (G -> H).The former route is followed by the alkoxycarbonylcarbenes and by 40; the ylides derived from the remaining carbenes do not react with methanol, owing to their rapid Stevens rearrangements.Protonation of the carbenes 17b, 31, and 53 is clearly indicated by their product ratios and, for 31, by the formation of isomeric ethers (33, 36).The more electrophilic carbenes discriminate but slightly between oxetane and methanol while the more nucleophilic carbenes (17b, 31, 53) prefer the protic methanol strongly over the aprotic oxetane. Key Words: Carbenes/ Oxygen ylides/ Stevens rearrangement/ Oxonium ions/ Insertion, O-H/ Ylides
- Kirmse, Wolfgang,Lelgemann, Rudolf,Friedrich, Klaus
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p. 1853 - 1863
(2007/10/02)
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- OXYGEN YLIDES-I. REACTIONS OF CARBENES WITH OXETANE
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The ylides generated from carbenes (:CH2, :CHCO2Et, :CHPh) and oxetane in the presence of methanol undergo Stevens rearrangement and protonation competitively, yielding tetrahydrofurans and 1,3-dialkoxycyclopropanes as major products.
- Friedrich, Klaus,Jansen, Ulrich,Kirmse, Wolfgang
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p. 193 - 196
(2007/10/02)
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- Rearrangements of Ylides Generated from Reactions of Diazo Compounds with Allyl Acetals and Thioketals by Catalytic Methods. Heteroatom Acceleration of the -Sigmatropic Rearrangement
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Allyl acetals undergo ylide generation in rhodium(II) acetate catalyzed reactions with diazo esters with subsequent production of 2,5-dialkoxy-4-alkenoates by the -sigmatropic rearrangement in moderate to good yields.The synthetic versatility of this class of polyfunctional compounds has been examined with selected transformations.Cyclopropanation and Stevens rearrangement compete with the -sigmatropic rearrangement in certain cases, and the influence of reactant structure and reaction conditions on this competition is reported.Comparative results with allyl ethers, which undergo cyclopropanation almost exclusively, demonstrate that heteroatom substitution on the allylic carbon accelerates ylide rearrangement.With dithioketals such as 2-ethenyl-2-methyl-1,3-dithiane, the ylide generated from Rh2(OAc)4 catalyzed reactions of ethyl diazoacetate undergoes -sigmatropic rearrangement in competition with intramolecular eliminination but without evidence of either cyclopropanation or Stevens rearrangement.Only when the -sigmatropic rearrangement cannot occur competitively does the Stevens rearrangement become important in reactions with dithioketals.In these examples the catalytic methodology for ylide generation is advanced as an attractive alternative to base promoted methodologies.
- Doyle, Michael P.,Griffin, John H.,Chinn, Mitchell S.,Leusen, Daan van
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p. 1917 - 1925
(2007/10/02)
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- Catalytic Role of Copper Triflate in Lewis Acid Promoted Reactions of Diazo Compounds
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Copper(II)trifluoromethanesulfonate is often a superior catalyst for transformations of diazo compounds that are normally promoted by boron trifluoride etherate.Formal carbon-oxygen insertion occurs when ortho esters are reacted with diazocarbonyl compounds in the presence of Cu(OTf)2, although the use of BF3*Et2O provides higher yields of insertion products.In contrast, the β,γ-unsaturated diazo ketone 6 undergoes intramolecular cyclization to produce the corresponding cyclopentenone in higher yield with Cu(OTf)2 catalysis than with the use of BF3*Et2O.Intamolecular cyclopropanation of the γ,δ-unsaturated diazo ketone 8 occurs in exceptionally high yield in the presence of Cu(OTf)2, whereas with BF3*Et2O intramolecular cyclization occurs with extensive rearrangement anf fluoride transfer.Copper(II)triflate is unique among transition-metal catalysts that are normally employed for reactions with diazo compounds in its effectiveness for these transformations.
- Doyle, Michael P.,Trudell, Mark L.
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p. 1196 - 1199
(2007/10/02)
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- 163. Reactions of Alkenediazonium Salts. Part 1. 2,2-Diethoxyethenediazonium Hexachloroantimonate: A Diazonium, a Carbenium or an Oxonium Salt?
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Reactions of the title compound 1 with various nucleophiles have been studied.The salt behaves like an alkylating agent towards ethers, alcohols and water forming ethyl diazoacetate (2), which reacts further with excess of the nucleophile.A solvent cage mechanism accounting for the observed products is proposed.Thermal decomposition in inert solvents leads to the alkylation of the counter-ion, i.e. formation of chloroethane, and in anisole, alkylation and chlorination of the solvent are also observed.With a standard coupling component, 2-naphtholate ion, no azo coupling reaction of 1 is observed, but instead 14-methyl-14H-dibenzoxanthene (17) is formed.The products of the reaction with diethylamine are diethylcyanoformamide (18) and ethyl diethylcarbamate (19).None of the chemistry of salt 1 is explained by the intervention of vinyl cations expected to be formed in a heterolytic dediazoniation.The predominant pathways seems to involve reactions of an oxonium salt (alkylating properties) or, in the case of diethylamine, a carbenium salt (primary nucleophilic attack on the β-C-atom of 1).The free energy barrier to C=C rotation in 1 is estimated to be 75 to 77 kJ/mol (18.0 to 18.5 kcal/mol), a value which falls between those expected for a double and a single bond.
- Szele, Ivanka,Tencer, Michal,Zollinger, Heinrich
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p. 1691 - 1703
(2007/10/02)
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