- Stereoselective synthesis of 1,6-dichloro-1,3,5-hexatriene derivatives by McMurry coupling of β-chloroacrylaldehyde derivatives
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A highly stereoselective synthesis of 1,6-dichloro-1,3,5-hexatriene derivatives by McMurry coupling of β-chloroacrylaldehydes have been developed.
- Gupta, Susmita,Kar, Gandhi K.,Ray, Jayanta K.
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- A Novel Catalyst-Free Synthesis of 2,2-Diaryl Enamides from Stilbenes via a Nitrene Transfer Reaction
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A novel catalyst-free nitrene transfer reaction between stilbenes and iminoiodinanes was achieved for the first time, which provides an efficient and environmentally friendly way to access variously substituted 2,2-diaryl enamides under mild conditions. Mechanistic investigations suggested the reaction proceed via nitrene transfer and aromatic rearrangement with iminoiodinane also acting as a Lewis acid, benefitting the ring-opening of the aziridine intermediate.
- Zhang, Yuanyuan,Ye, Wenjing,Zhang, Hui,Xiao, Xiao
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supporting information
p. 5720 - 5724
(2019/08/26)
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- Facile utilisation of aldehyde bisulfite adducts: Synthesis of (E)-1,2- diphenylethenes
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Background: A one-pot coupling reaction of aldehyde bisulfite adducts was developed for McMurry reaction using Zn-TiCl4 in 1,4-dioxane solvent medium. The treatment of sodium hydroxy(phenyl)methane sulfonate (2a) with TiCl4 in 1,4-dioxane favoured the deprotection of the bisulfite adduct 2a, and the in situ regeneration of benzaldehyde (1a) underwent reductive coupling to afford stilbene 3a in a relatively good yield, thus leading to an improved synthesis of a series of (E)-1,2- diphenylethenes 3. The present approach provides a new solution to the inherent instability of aldehydes and also provides a direct access to C'C bond formation for the synthesis of 1,2-diphenylethenes from aryl aldehyde bisulfite adducts. Methods: All reactions were performed at 70-80o and the synthesized compounds were characterized by IR, 1H NMR, 13C NMR, and mass spectrometric techniques. Results: The present approach provides a new solution to the instability of aldehydes and also provides a direct access to C'C bond formation for the synthesis of 1,2-diphenylethenes from aryl aldehyde bisulfite adducts. Conclusion: In the present work, we have reported an efficient method for the synthesis of 1,2- diphenylethene derivatives. Aldehydes are commonly used as the starting materials in the McMurry reaction, which affords the stilbene derivatives, the core skeleton of various valuable compounds. To increase the stability of the aldehydes, bisulfite adducts are usually employed, but the deprotection process causes loss of process efficiency. To address this issue, we developed a method based on the single-pot reaction of aromatic bisulfite adduct using TiCl4/Zn in 1,4-dioxane.
- Vinay Kumar,Jaganmohan,Sandeep Reddy,Mohanty, Sandeep,Kumar, Jaydeep,Rao, Venkateswara
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p. 109 - 114
(2017/04/03)
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- Copper-catalyzed double intramolecular ullmann coupling for the synthesis of diastereomerically and enantiomerically pure 4b,9b-dihydrobenzofuro[3,2-b]benzofurans
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The copper-catalyzed double intramolecular Ullmann coupling of syn-1,2-bis(2-bromoaryl)ethane-1,2-diols with catalytic amounts of CuII oxinate as the copper source, K3PO4 as a base, and KI as a reductant in aqueous acetoni
- Imrich, Hans-Georg,Conrad, Jürgen,Beifuss, Uwe
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p. 7718 - 7734
(2015/12/31)
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- Synthesis of 2-bromo-1-aryl-1H-indenes via a Ag(I) promoted domino 2π-electrocyclic ring-opening/4π-electrocyclization reaction of 1,2-diaryl substituted gem-dibromocyclopropanes
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2-Bromo-1-aryl substituted indenes can be synthesized from 1,2-diaryl substituted gem-dibromocyclopropanes via a domino reaction sequence. The cascade reaction involves silver(I) promoted ionization and 2π-disrotatory electrocyclic ring-opening, followed by a 4π-conrotatory electrocyclic ring closing reaction of the allylic carbocation intermediate. Reaction conditions utilize silver tetrafluoroborate (AgBF4) in dichloroethane at 65 C. Selectivity effects for the electrocyclization were also studied. The 2-bromoindenes can be further functionalized using cross-coupling reactions, such as the Suzuki-Miyaura protocol. The alkene π-bond of the indenes can also be isomerized to give the thermodynamically more stable 2-bromo-3-aryl-1H-indene isomers using triethylamine in dichloromethane at room temperature.
- Rosocha, Gregory,Batey, Robert A.
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p. 8758 - 8768
(2013/09/23)
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- Synthesis of stilbene analogues by one-pot oxidation-Wittig and oxidation-Wittig-Heck reaction
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Synthesis of symmetrical (and unsymmetrical) stilbene derivatives is achieved by a combination of one-pot steps of Kornblum type oxidation of benzyl halide, its simultaneous in situ formation of phosphonium salt, and subsequently their Wittig reaction. In other variant it is oxidized to aldehyde, treated with ylide generated from phosphonium salt (CH3PPh3X) to give styrene, and subjected to Pd catalyzed Heck reaction with arylhalide to give stilbenes as the three-step one-pot sequence.
- Saiyed, Akeel S.,Patel, Krupa N.,Kamath, Bola V.,Bedekar, Ashutosh V.
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supporting information; experimental part
p. 4692 - 4696
(2012/09/10)
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- Unequivocal experimental evidence for a unified lithium salt-free wittig reaction mechanism for all phosphonium ylide types: Reactions with β-heteroatom-substituted aldehydes are consistently selective for cis-oxaphosphetane-derived products
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The true course of the lithium salt-free Wittig reaction has long been a contentious issue in organic chemistry. Herein we report an experimental effect that is common to the Wittig reactions of all of the three major phosphonium ylide classes (non-stabilized, semi-stabilized, and stabilized): there is consistently increased selectivity for cis-oxaphosphetane and its derived products (Z-alkene and erythro-β-hydroxyphosphonium salt) in reactions involving aldehydes bearing heteroatom substituents in the β-position. The effect operates with both benzaldehydes and aliphatic aldehydes and is shown not to operate in the absence of the heteroatom substituent on the aldehyde. The discovery of an effect that is common to reactions of all ylide types strongly argues for the operation of a common mechanism in all Li salt-free Wittig reactions. In addition, the results are shown to be most easily explained by the [2+2] cycloaddition mechanism proposed by Vedejs and co-workers as supplemented by Aggarwal, Harvey, and co-workers, thus providing strong confirmatory evidence in support of that mechanism. Notably, a cooperative effect of ortho-substituents in the case of semi-stabilized ylides is confirmed and is accommodated by the cycloaddition mechanism. The effect is also shown to operate in reactions of triphenylphosphine-derived ylides and has previously been observed for reactions under aqueous conditions, thus for the first time providing evidence that kinetic control is in operation in both of these cases.
- Byrne, Peter A.,Gilheany, Declan G.
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supporting information; experimental part
p. 9225 - 9239
(2012/07/14)
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- Convenient and stereoselective synthesis of symmetrical (E)-stilbenes via homocoupling of 1,3-dibenzylbenzotriazolium bromides
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Using NaH as the base and DMSO as the solvent, a series of symmetric (E)-stilbenes were prepared in good yields via the -homocoupling of 1,3-dibenzylbenzotriazolium bromides at room temperature. Georg Thieme Verlag Stuttgart · New York.
- Xiao, Xiaohui,Lin, Daqin,Tong, Shuitian,Luo, Hong,He, Yinfeng,Mo, Hailan
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supporting information; experimental part
p. 1731 - 1734
(2011/09/16)
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- Tandem pinacol coupling-rearrangement of aromatic aldehydes with hydrogen catalyzed by a combination of a platinum complex and a polyoxometalate
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Together with a strongly oxidizing polyoxometalate, H5PV 2Mo10O40, PtII(N-(2,6- diisopropylphenyl)pyrazin-2-ylmethanimine)Cl2 forms a combined catalyst that was active in the tandem pinacol coupling-rearrangement of aryl aldehydes to give mostly the corresponding diarylacetaldehyde in high yields using molecular hydrogen as the reducing agent. The Royal Society of Chemistry.
- Branytska, Olena,Shimon, Linda J. W.,Neumann, Ronny
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p. 3957 - 3959
(2008/10/09)
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- Co-operative ortho-effects on the Wittig reaction. Interpretation of stereoselectivity in the reaction of ortho-halo-substituted benzaldehydes and benzylidenetriphenylphosphoranes
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The E/Z ratios of the stilbenes 1 formed in the Wittig reaction of ortho-halo substituted benzyltriphenylphosphonium salts 2 and benzaldehydes 3 were determined. It was found that there is a co-operative effect of one ortho-halo group on each of the two reacting partners which increases Z-selectivity, but two such groups on the same reactant gives high E-selectivity. The effects are strong enough to be preparatively significant in certain cases and can be interpreted within the modern framework of the Wittig mechanism established by Vedejs and co-workers.
- Dunne, Eoin C,Coyne, éamonn J,Crowley, Peter B,Gilheany, Declan G
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p. 2449 - 2453
(2007/10/03)
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- Synthesis, X-ray structures and chemistry of enantiomerically pure 10,11-dihydro-5-phenyl-5H-dibenzo[b,f]phosphepine 5-oxides
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Several phosphepine oxides were synthesised in optically pure form. Sharpless asymmetric dihydroxylation was used to introduce the chiral centres in all cases. Ring closure was achieved using either PhPCl2 or PrPCl2 together with a double nucleophile generated by either a double ortho-lithiation or double bromine-lithium exchange. The X-ray crystal structures of three phosphepine oxides illustrate their different conformations. The NMR spectra of several phosphepine oxides are described as is the chemistry which is shown to differ from that of acyclic phosphine oxides.
- Wyatt, Paul,Warren, Stuart,McPartlin, Mary,Woodroffe, Tom
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p. 279 - 297
(2007/10/03)
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- Secondary Reactions of Sulfenes from Sulfonyl Chlorides and Tertiary Amines. 2. Formation of Episulfones, Sulfonylsulfene - Amine S,N-Adducts and Chlorsulfines from Primary Sulfonyl Chlorides and Tertiary Amines
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The reaction of primary sulfonyl chlorides 1b-m with the tertiary amine bases quinuclidine, DABCO, Me3N, Et3N, Bu3N, EtiPr2N, and 1,2,2,6,6-pentamethylpiperidine is studied in acetonitrile solution between -40 and 80 deg C.The 2,3-dialkylthiirane 1,1-dioxides 4 (trans/cis > 1) and the alkenes 5 1> are obtained in high yields with Et3N at -40 deg C.The stereochemistry is influenced by the amine base B in the ring-closure reaction and partially by epimerization of the episulfones 4.Hindered bases favor the cis, β-branched sulfonyl chlorides the trans isomer.Competing formation of the sulfonylsulfene - amine S,N-adducts 7 is only observed with quinuclidine, DABCO, and Me3N, which are also the most active amines in the epimerization of the cis-2,3-diarylthiirane 1,1-dioxides 4.Methanesulfonyl chloride (1a) yields the mesylsulfene - amine S,N-adducts 7a with Me3N and Et3N in MeCN, but thiirane 1,1-dioxide (4a) with EtiPr2N in MeCN or with Et3N in Et2O.Formation of chlorosulfines 10 is favored by higher temperature (T > 20 deg C), hindered amine bases and β-branched sulfonyl chlorides.Isolation of 10g and 10h in high yields shows that tert-alkylchlorosulfines are rather stable sulfines.
- Opitz, Guenter,Ehlis, Thomas,Rieth, Karlheinz
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p. 1989 - 1998
(2007/10/02)
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- ZEOLITE-CuNaY CATALYZED DECOMPOSITION OF ARYLDIAZOMETHANE
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Decomposition of aryldiazomethanes is catalyzed by copper ion-exchanged Y-type zeolite to afford cis-1,2-diarylethylenes in high selectivity.The catalytic activity and selectivity are found to be affected by the exchange level of copper ions in zeolite and the solvent used.
- Onaka, Makoto,Kita, Hiroshi,Izumi, Yusuke
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p. 1895 - 1898
(2007/10/02)
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- sym-1,2-Diarylethylenes from α-Lithiated Benzylic Sulfones. Catalysis by Elemental Tellurium
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The stability of α-lithiated alkyl, allyl, and benzyl phenyl sulfones was studied. α-Lithiated benzyl phenyl sulfones were found to give sym-1,2-diarylethylenes slowly when kept in tetrahydrofuran at ambient temperature for several days.The reaction time was significantly reduced if a catalytic amount (18-24percent) of elemental tellurium was present in the reaction.Other chalcogenides were less effective in this respect.The uncatalyzed reaction produced essentially pure trans olefins whereas the tellurium-catalyzed process afforded substantial amounts of cis isomer(usually 15-35percent).Tellurium tetrachloride in chloroform at ambient to reflux temperature was found to be highly effective in promoting cis/trans isomerization of 1,2-diarylethylenes.The involvement of a carbene mechanism or an intermolecular reaction of α-lithiated benzyl phenyl sulfones is considered in a mechanistic discussion.
- Engman, Lars
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p. 3559 - 3563
(2007/10/02)
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- REACTION OF ARYLMETHANESULFONYL AND STYRYLMETHANESULFONYL CHLORIDES WITH TRIETHYLAMINE
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A series of arylmethanesulfonyl chlorides were treated with triethylamine in THF to give stilbenes in excellent yields.Workup of the mixtures below 10 deg C permits isolation of stilbene episulfones which on warming decompose to yield the corresponding stilbenes stereospecifically.Application of the reaction to 9-fluorenylsulfonyl chloride affords bifluorenylidene, while trans-styrylmethanesulfonyl chloride gives 4,5-dihydro-4,5-diphenylthiepin 1,1-dioxide and 1,6-diphenylhexatriene.
- Nakayama, Juzo,Tanuma, Mitsuru,Honda, Yoshiko,Hoshino, Masamatsu
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p. 4553 - 4556
(2007/10/02)
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- CONVERSION OF DISILANES TO FUNCTIONAL MONOSILANES. XIII. THE PALLADIUM CATALYZED REDUCTIVE COUPLING OF BENZYLIDENE DICHLORIDES AND BENZYLIDYNE TRICHLORIDES USING DISILANES AS REDUCING AGENTS.
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The reaction of benzylidene dichlorides or benzylidene trichlorides with 1,2-dichloro-1,1,2,2-tetramethyl-disilane or hexamethyldisilane proceeded smoothly in the presence of a catalytic amount of Pd(PPh//3)//4 to give (E)-stilbenes or (E)- and (Z)- alpha beta -dichlorostilbenes in high yields, respectively. Also, in the presence of the palladium (0) catalyst, alpha , alpha -dichlorobenzyltrimethylsilanes reacted with hexamethyldisilane yielding (E)- alpha , beta -bis(trimethylsilyl)stilbenes in quantitative yield.
- Matsumoto,Arai,Takahashi,Ashizawa,Nakano,Nagai
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p. 3009 - 3014
(2007/10/02)
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- HIGH-TEMPERATURE ORGANIC SYNTHESIS. XXII. THERMAL TRANSFORMATIONS OF EXO-CHLORINE-SUBSTITUTED TOLUENES
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The gas-phase pyrolysis of exo-chlorine-substituted toluenes in an atmosphere of nitrogen or hydrogen sulfide was investigated.Hydrogen sulfide stimulates the thermolysis of benzyl chloride, accelerating the formation of toluene and stilbene at 430 deg C.The other reaction products are anthracene and bibenzyl.Similar compounds and also phenanthrene are formed during the pyrolysis of benzylidene chloride in an atmosphere of nitrogen or hydrogen sulfide (500 deg C).Benzotrichloride is distinguished by its high stability; its pyrolysis mainly with the formation of 1,2-dichloro-1,2-diphenylethylene is realized at temperatures above 550 deg C.With hydrogen sulfide it reacts at 400 deg C to form bibenzyl, stilbene, anthracene, phenanthrene, and thianaphtenothianaphthene.The latter is the main product in a recirculation-type system.
- Voronkov, M. G.,Deryagina, E. N.,Shagun, L. G.,Vitkovskii, V. Yu.
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p. 962 - 966
(2007/10/02)
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- Sigmatropic Rearrangement of Ylides Derived from Benzylic Selenonium Salts
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The sigmatropic rearrangement of a series of ylides derived from benzylic selenonium salts has been observed.These ylides alkyl or aryl o-methylbenzyl selenides.The competition between nucleophilic displacement and ylide formation in the reaction of base with benzylic selenonium salts has been evaluated.
- Gassman, Paul G.,Miura, Takashi,Mossman, Allen
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p. 954 - 959
(2007/10/02)
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- RHODIUM ION CATALYZED DECOMPOSITION OF ARYLDIAZOALKANES
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Aryldiazomethanes are converted by rhodium(II)acetate and iodorhodium(III) tetraphenylporphyrin to cis- rather than trans-1,2-diarylethylenes.Secondary aryldiazoalkanes react with rhodium(II) acetate to give azines.
- Shankar, B.K. Ravi,Shechter, Harold
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p. 2277 - 2280
(2007/10/02)
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- THE PALLADIUM(0)-CATALYZED REDUCTIVE COUPLING OF HALIDES USING sym-DICHLOROTETRAMETHYLDISILANE AS A REDUCING AGENT
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The eraction of benzylidene chlorides as well as 1,2-dihalogeno-1,2-diphenylethanes with sym-dichlorotetramethyldisilane in the presence of a catalytic amount of tetrakis(triphenylphosphine)palladium(0) gave aryl-substituted ethenes in good yields.
- Nakano, Taichi,Takahashi, Masatoshi,Ashizawa, Toshiyuki,Arai, Takeshi,Seki, Shinji,et al.
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p. 613 - 616
(2007/10/02)
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