- Synthesis of (14C6-3,4,7,8,11,12)-(1E,5E,9E)- cyclododeca-1,5,9-triene
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Trimerization of butadiene in the presence of Ni(0) affords (1E,5E,9E)-cyclododeca-1,5,9-triene 1 (ttt-CDT), (1E,5E,9Z)-cyclododeca-1,5,9- triene 2 (ttc-CDT), and other isomers/oligomers. After optimization of reaction conditions, [14C6-3,4,7,8,11,12]-ttt-CDT 1 was synthesized efficiently either by homogenous or heterogeneous Ni(0) catalytic trimerization of [1,4-14C2]butadiene 10, in 60-82% yield. Depending on the exact reaction conditions employed, the yields and ratio of 1/2 ranged from (59-90%) / (41-10%). The all-trans isomer was conveniently isolated via Ag +-mediated reversed-phase HPLC. The important intermediate [1,4- 14C2]-1,3-butadiene 10 was prepared from potassium [ 14C]cyanide and 1,2-dibromoethane 3 as starting materials, in seven steps with a 57% yield. The total radioactive yield of [14C 6-3,4,7,8,11,12]-ttt-CDT 1 is 30% from [14C]KCN. Copyright
- Diel, Bruce N.,Han, Mingcheng,White, Jonathan M.
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p. 407 - 409
(2008/02/08)
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- A new method of synthesis of cyclododecyl ethers
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Cyclododecyl ethers were synthesized by substitutive alkoxylation of isomeric acetoxycyclododeca-2,6,10-trienes with aliphatic alcohols in the presence of Pd[PPh3]4, followed by hydrogenation of the double bonds. The kinetics of the substitutive alkoxylation of isomeric cyclododecatrien-1-yl acetate with 2-methoxyethanol at 358°C were studied.
- Balbolov,Mitkova
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- Nickel(0) and palladium(0) complexes with 1,3,5-triaza-7-phosphaadamantane. Catalysis of buta-1,3-diene oligomerization or telomerization in an aqueous biphasic system
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New homoleptic nickel(0) and palladium(0) complexes with a water-soluble ligand, 1,3,5-triaza-7-phosphaadamantane, were prepared and characterized by 1H, 13C, and 31P NMR spectra. The complexes, together with the known ana
- Cermak, Jan,Kvicalova, Magdalena,Blechta, Vratislav
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p. 355 - 363
(2007/10/03)
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- Titanium-catalyzed [4+2] and [6+2] cycloadditions of 1,4-bis(trimethylsilyl)buta-1,3-diyne
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The (C2H5)2AlCl/TiCl4 catalyst induces the [4+2] cycloaddition of butadiene or the [6+2] cycloaddition of 1,3,5-cycloheptatriene (CHT) to individual acetylenic moieties of 1,4-bis(trimethylsilyl)buta-1,3-diyne (BSD). Heating of the 2:1 butadiene adduct, bis(2-trimethylsilylcyclohexa-1,4-dien-1-yl), to 250°C yields 2,2′-bis(trimethylsilyl)biphenyl. The 1:1 adduct of BSD with CHT, 7-trimethylsilyl-8-trimethylsilylethynylbicyclo[4.2.1]nona-2,4-diene, is obtained as virtually the only product if the initial molar ratio CHT:BD equal to 1.86 is used.
- Kaagman, Jan-Willem F.,Rep, Marco,Horacek, Michal,Sedmera, Petr,Cejka, Jiri,Varga, Vojtech,Mach, Karel
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p. 1722 - 1728
(2007/10/03)
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- (Z)-(E) Interconversion of Olefins by the Addition-Elimination Sequence of the (TMS)3Si(.) Radical
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Tris(trimethylsilyl) radical is effective inisomerizing either acyclic or cyclic olefins by an addition-elimination sequence.The E/Z ratio after equilibration generally reflects the thermodynamic stability of (Z)- and (E)-alkenes.It has been shown for (E)- and (Z)-hexen-1-ol that equilibration (Z/E = 18/82) is reached with the (TMS)3Si(.) radical in 10 h at 80 deg C, whereas with PhS(.) and Bu3Sn(.) radicals the same isomeric composition is reached in 1 and 4 h, respectively.In cyclic systems like (Z)-cyclododecene the ratio of Z/E = 46/54 is reached in 8 h, while with PhS(.) and Bu3Sn(.) it is much slower.An explanation of this phenomenon has been advanced.Additional information on the impact of this addition-elimination methodology in organic synthesis is given.
- Chatgilialoglu, C.,Ballestri, M.,Ferreri, C.,Vecchi, D.
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p. 3826 - 3831
(2007/10/02)
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- The crystal structure of (η6-C6Me6)Ti2 and the catalytic activity of the (C6Me6)TiAl2Cl8-xEtx (x = 0-4) complexes towards butadiene
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The composition of (C6Me6)TiAl2Cl8-xEtx complexes in (C6Me6)TiAl2Cl8 + n Et3Al (n = 0.5-6) systems was studied by UV-Vis spectroscopy and the X-ray crystal structure of one of them, (η6-C6Me6)Ti2 (IIa-2), has been determined.The complex crystallizes in the orthorhombic space group Pna21 with Z = 4 and lattice parameters a 15.634(3), b 11.355(2), c 14.417(a) Angstroem.The ethyl groups of IIa-2 reside in outer positions of aluminate ligands farther away from the C6Me6 ligand.The other part of the complex does not differ remarkably from structures of other (arene)TiII complexes.Negligible activity of (C6Me6)TiAl2Cl8 towards the butadiene cyclotrimerization is considerably increased by addition of 2.5-3.0 equivalents of Et3Al.As follows from UV-Vis spectra, such systems contain mainly the (C6Me6)TiAl2Cl5Et3 complex.It is suggested that the introduction of three Et substituents destabilizes the Ti-(η6-C6Me6) bond so that the replacement of hexamethylbenzene by butadiene in the first step of a catalytic cycle becomes more feasible.
- Troyanov, Sergei I.,Polacek, Jindrich,Antropiusova, Helena,Mach, Karel
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p. 317 - 325
(2007/10/02)
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- EFFECT OF TRIPHENYLPHOSPHINE ON THE CYCLOTRIMERIZATION OF BUTADIENE CATALYZED BY THE TiCl4-EtAlCl2 SYSTEM
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Addition of PPh3 to the TiCl4 + n EtAlCl2 (n = 4-10) systems, which normally exhibit mostly Friedel-Crafts and polymerization activity towards butadiene, turns these systems into highly specific catalysts for the cyclotrimerization of butadiene to (Z, E, E)-1,5,9-cyclododecatriene.The effect of PPh3 lies in removal of AlCl3, which is formed in the reduction of TiCl4 with EtAlCl2 and in the disproportionation of EtAlCl2, for the AlCl3.PPh3 complex displays higher stability in comparison with the analogous complexes with ethylaluminium chlorides.The composition of the (η6-benzene)Ti(II) complexes, which are the catalytically active species, was determined by electronic absorption spectroscopy in the post-reaction mixtures.
- Polacek, Jindrich,Antropiusova, Helena,Petrusova, Lidmila,Mach, Karel
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p. 1756 - 1762
(2007/10/02)
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- ISOMERIZATION OF TRANS-1,2-EPOXY-CIS,TRANS-5,9-CYCLODODECADIENE, TRANS-1,2-EPOXY-TRANS,TRANS-5,9-CYCLODODECADIENE, AND TRANS-EPOXYCYCLODODECANE TO THE CORRESPONDING KETONES BY THE ACTION OF LITHIUM AND MAGNESIUM IODIDES AND BROMIDES
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The isomerization of trans-1,2-epoxy-cis,trans-5,9-cyclododecadiene, trans-1,2-epoxy-trans,trans-5,9-cyclododecadiene, and trans-epoxycyclododecane by the action of lithium and magnesium iodides and bromides leads to the formation of the corresponding 12-membered cyclic ketones and is not accompanied by ring contraction.
- Zakharkin, L. I.,Guseva, V. V.,Kamernitskii, D. A.,Tsvetkov, V. F.,Likhomanenko, V. A.
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p. 1291 - 1294
(2007/10/02)
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- THE INFLUENCE OF ALKALI METAL HALIDES ON THE BUTADIENE CYCLOTRIMERIZATION CATALYZED BY (BENZENE)TITANIUM(II) COMPLEXES
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Addition of alkali chlorides (MCl) to (η6-C6H6)Ti(AlCl4)2 (Ia) decreases the catalytic activity of Ia while the selectivity of the (Z,E,E)-1,5,9-cyclododecatriene formation is improved only when NaCl is used at the optimum molar ratio NaCl/Ia ca 5.The alkali chlorides remove free AlCl3, which is present in the system as an admixture, probably in the form of MAlCl4 complexes; however, an excess of MCl brings about decomposition of catalytic trinuclear Ti(II) complexes during the butadiene cyclotrimerization.In addition to inactive TiCl2, this decomposition yields some AlCl3 which induces the formation of cationic byproducts, 1-phenylbut-2-ene and (E)-1,4-poly(butadiene), before it is deactivated or quenched with MCl.
- Polacek, Jindrich,Petrusova, Lidmila,Antropiusova, Helena,Mach, Karel
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p. 1839 - 1845
(2007/10/02)
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- Polymer supported 2,2'-dipyridylmethane: catalytic activity of transition metal complexes in hydrogenations and oligomerizations
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The palladium(II) acetate complex of the chelating ligand 2,2'-dipyridylmethane supported on polystyrene-2percent divinylbenzene is an efficient catalyst for hydrogenation of alkenes and alkynes.Cyclopentadiene can be reduced with high selectivity to cyclopentene, but no selectivity is observed for the non-conjugated diene 1,5-cyclooctadiene.In the hydrogenation of 3-methylcyclohex-2-en-1-ol only small amounts of ketone are formed as a by-product, in contrast to the reaction catalysed by palladium on charcoal.Nickel(II) complexes of the same ligand catalyze the trimerization of butadiene to 1,5,9-cyclododecatrienes.
- Moberg, Christina,Rakos, Laszlo
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p. 125 - 132
(2007/10/02)
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- DEACTIVATION OF ARENETITANIUM(II) BROMOALANE COMPLEXES IN THE CYCLOTRIMERIZATION OF BUTADIENE
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The C6H6*Ti(II)(AlBr4)2 (Ib) catalyst deactivates during the butadiene cyclotrimerization to give a solid containing all titanium (mostly as TiBr3) and a mixture of AlBr3 and RAlBr2 compounds dissolved in benzene.The residual cationic catalytic activity of the deactivated Ib system is due to presence of AlBr3.In contrast to TiCl3, the deactivated Ib system and the model system TiBr3 + AlBr3 are not activated by the addition of EtAlCl2 in the presence of butadiene: the highly active benzenetitanium(II) system is re-constituted only after reduction of TiBr3 with Et3Al followed by the addition of EtAlCl2.The addition of Et2AlBr to Ib accelerates the deactivation of the system.Deactivation products of this system contain mainly Ti(II) species which forms benzenetitanium(II) catalytic system after addition of EtAlCl2.All the EtAlCl2 reactivated system produce (Z,E,E)-1,5,9-cyclododecatriene with high catalytic stability and considerable selectivity (>90percent).This behaviour points to the catalysis by benzenetitanium(II) chloroalane complexes containing only low amount of bromine atoms and ethyl groups.
- Polacek, Jindrich,Antropiusova, Helena,Petrusova, Lidmila,Mach, Karel
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p. 2751 - 2759
(2007/10/02)
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- STRAINED CYCLOALKENYNES
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Presently known strained cycloalkynes with one, two or three additional cis- or trans-configurated double bonds are summarized in Table 3.The main topics of the article are the geometrical ring strain, the preparation or in situ generation of these compounds by fragmentation of the corresponding 1,2,3-selendiazoles, and the thermal isomerisation processes performed at room temperature or in flash pyrolysis experiments at 440-640 deg C.
- Meier, Herbert,Hanold, Norbert,Molz, Thomas,Bissinger, Hans Joachim,Kolshorn, Heinz,Zountsas, Johannes
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p. 1711 - 1720
(2007/10/02)
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- THERMAL CONVERSION OF 1,5,9-TRIYNES. CYCLOADDITIONS OR SIGMATROPIC SHIFTS?
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The gas phase pyrolyses of variously labeled 1,5,9-decatriynes (1) and 1,5,9-cyclododecatriynes (2) were investigated to determine possible modes of thermal isomerizations.Conditions included temperatures in the range 400-600 deg C, pressures of 40 -10E-4 Torr, and contact times of ca 1 ms to 15 s.The labeling patterns in 1 and 2 were chosen such as to be able to distinguish direct intramolecular cycloadditions of the alkyne units to form an aromatic ring (perhaps with subsequent rearrangements), and sigmatropic shifts of the 1,5-diyne moieties.Methods for synthesizing the isotopically (particularly (13)C) labeled triynes were devised and implemented.The route to 5,6-(13)C2-1,5,9-decatriyne (1c) made use of a new procedure for the synthesis of symmetrically disubstituted alkynes involving coupling between two equivalents of an alkyl copper reagent and diiodoacetylene-(13)C2.The synthesis of 1,10-(13)C2-1,5,9-cyclododecatriyne (2b) was accomplished starting with K(13)CN, elaboration to labeled diethyl succinate, a crucial bis-Wittig condensation to labeled 1,5,9-cyclododecatriene 10, and bromination-dehydrobromination of the latter (NaOH-ethylene glycol).Products from the pyrolysis of unlabeled 1a included dicyclobutabenzene, naphtalene and 3,4-dimethylidene-1-(but-3-ynyl)cyclobutene.Pyrolysis of 1b gave 3,6-dideuteriodicyclobutabenzene and partially deuterated naphthalene, that of 1c produced 1,2-(13)C2-dicyclobutabenzene and 9,10-(13)C2-naphthalene.While the pyrolysis of 2a resulted in hexamethylidenecyclohexane (hexaradialene), 2b furnished 1,4-(13)C2-hexaradialene.The results rule out the occurence of cycloadditions of the alkyne units, but are consistent with the intervention of a series sigmatropic shifts which connect starting materials with products.
- Dower, William V.,Vollhardt, K. Peter C.
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p. 1873 - 1882
(2007/10/02)
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- TITANIUM-CATALYZED DIELS-ALDER CYCLOADDITION OF CONJUGATED DIENES TO BIS(TRIMETHYLSILYL)ACETYLENE. 1,2-BIS(TRIMETHYLSILYL)CYCLOHEXA-1,4-DIENE, 1,2-BIS(TRIMETHYLSILYL)BENZENE, AND THEIR METHYL DERIVATIVES
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The catalytic system Et2AlCl/TiCl4 induces Diels-Alder cycloaddition of bis(trimethylsilyl)acetylene to 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene and (E)-1,3-pentadiene affording 1,2-bis(trimethylsilyl)cyclohexa-1,4-dienes in high yields.The cyclohexadienes are readily converted to the corresponding 1,2-bis(trimethylsilyl)benzenes upon heating to 240 deg C.Mass, infrared, 1H, 13C and 29Si NMR spectra of all the products obtained are reported and briefly discussed.The crowded character of aromatic compounds is reflected in their mass, 13C and 29Si NMR spectra.
- Mach, K.,Antropiusova, H.,Petrusova, L.,Turecek, F.,Hanus, V.,et al.
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p. 331 - 340
(2007/10/02)
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- Multi Electron Ligands, VIII. Connection of the all-trans-1,5,9-Cyclododecatriene System with Additional Donor Groups
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Nine potential ligands (2 - 10) for transition metals were obtained from the well accessible all-trans-1,5,9-cyclododecatriene (ttt-CDT) by introduction of donor groups.The synthesis was achieved via ttt-3-bromo-CDT (1) and the hitherto unknown ttt-3-iodo-CDT (2).To the contrary, introduction of donor groups via nucleophilic ttt-CDT derivatives was successful in one case only (15). ttt-3-Lithio-CDT (13), obtained by organoelement-Li exchange, revealed to be extremely basic (quick deprotonation of diethyl ether at low temperature).In situ made Ni0 complexes of someof the new ligands failed to oligomerize or polymerize butadiene.
- Kauffmann, Thomas,Fauss, Waltraud
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p. 2330 - 2342
(2007/10/02)
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- CYCLOADDITIONS CATALYZED BY TITANIUM COMPLEXES
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The Ziegler catalyst TiCl4-Et2AlCl and the arenetitanium(II) complex (η6-C6H6)Ti(II)(AlCl4)2 induce cycloaddition reactions of cycloheptatriene with dienes and acetylenes.Addition to 1,3-butadiene affords 7-endo-vinyl-bicyclonona-2,4-diene (main product) and bicyclo-undeca-2,4,8-triene, a product of cycloaddition.Isoprene reacts similarly, yielding mainly 7-endo-isopropenyl-bicylonona-2,4-diene. 2,3-Dimethyl-1,3-butadiene gives 8,9-dimethylbicycloundeca-2,4,8-triene, a product of cycloaddition, while cross-adducts are minor products.The reaction of cycloheptatriene with norbornadiene gives mainly hexacyclo2.7.03.12.06.10.09.13>tetradec-4-ene via cycloaddition followed by intramolecular Diels-Alder reaction.As a by-product, pentacyclo2.7.03.5.04.8>tetradeca-10,12-diene is formed by a mechanism.Addition of cycloheptatriene to phenylacetylene and bis-(trimethylsilyl)acetylene furnishes substituted bicyclonona-2,4,7-trienes.Alkenes, E,E-2,4-hexadiene and 1,3-cyclooctadiene are unreactive.The cycloaddition is made possible by coordination of cycloheptatriene to titanium, which changes the symmetry of the frontier orbitals in the triene.The reactivity of the trienophile is also enhanced by coordination to the catalyst.
- Mach, Karel,Antropiusova, Helena,Petrusova, Lidmila,Hanus, Vladimir,Turecek, Frantisek,Sedmera, Petr
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p. 3295 - 3302
(2007/10/02)
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- CIS-TRIS--?-HOMOBENZENE - SYNTHESIS AND THERMOLYSIS
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The cis-tris--?-homobenzene 7 has been synthesised.From vapour phase thermolyses (400-500 deg C) it is concluded, that the ?2s+?2s+?2s>-cycloreversion reaction is - at most - only a minor pathway in the thermal stabilisation of 7.
- Maas, M.,Lutterbeck, M.,Hunkler, D.,Prinzbach, H.
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p. 2143 - 2146
(2007/10/02)
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- ?6s + ?2s> Cyloadditions Catalysed by the TiCl4-Et2AlCl System
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The catalyst system TiCl4-Et2AlCl induces ?6s + ?2s> cycloadditions of cycloheptatriene to buta-1,3-diene, norbornadiene, and acetylenes.
- Mach, Karel,Antropiusova, Helena,Sedmera, Petr,Hanus, Vladimir,Turecek, Frantisek
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p. 805 - 806
(2007/10/02)
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