Elektrochemische synthesen metallorganischer verbindungen III. Darstellung und umwandlung von π-cyclooctenyl-1,5-cyclooctadiencobalt

By electrolysis of cobalt(II)-acetylacetonate in the presence of 1,5-cyclooctadiene there is obtained π-cyclooctenyl-1,5-cyclooctadienecobalt (I). By heating of I to 60° in 1,5-cyclooctadiene, π-bicyclo[3.3.0]octadienyl-(1,5-cyclooctadiene)cobalt (II) and cyclooctene are formed.     

Synthesis and utilization of alternative chain transfer agent in cobalt catalyzed 1,3-butadiene polymerization reaction to produce cis-polybutadiene rubber

The cyclodimerization of 1,3-butadiene was performed to synthesize 1,5-cyclooctadiene by using nickel-phosphite based catalyst system. The optimization of cyclodimerization reaction was done to achieve up to 80% selectivity towards 1,5-cyclooctadiene. 1,5-Cyclooctadiene, thus synthesized, was subsequently employed as a chain transfer agent (CTA) for controlling the molecular weight (M.W.) of cis-polybutadiene rubber (BR) in cobalt-complex catalyzed 1,3-butadiene polymerization reaction. The M.W. of BR was reduced from 6.7 to 1.88 × 10⁵ g/mol by escalating the concentration of 1,5-cyclooctadiene from 0% to 0.5% with respect to 1,3-butadiene (monomer) concentration. Similar reducing trend was observed for the Mooney viscosity and gel content of BR with increasing 1,5-cyclooctadiene concentration. The efficacy of 1,5-cyclooctadiene as a CTA for 1,3-butadiene polymerization reaction was further explored by conducting polymerization reaction in various solvents and at higher monomer conversion (∼70%). The effect of 4-vinyl cyclohexene, which was a dominant byproduct during cyclodimerization of 1,3-butadiene, was also investigated. The presence of 4-vinyl cyclohexene has shown adverse effect in the polymerization reaction and was not functioning as a chain transfer agent. Finally, a feasibility of replacement of commercially used gaseous CTA, 1,2-butadiene, by in-house synthesized liquid CTA, 1,5-cyclooctadiene, was also investigated.     

Metathesis copolymerization of 1,5-cyclooctadiene and norbornene with electrochemically generated WCl6-based active species

The copolymerization of 1,5-cyclooctadiene and norbornene in the presence of an electrochemically generated WCl₆-based catalyst was investigated. This copolymer was isolated and characterized by ¹H, and ¹³C NMR spectroscopy to analyse in detail the nature of homo- and heterodyad units and GPC analysis (Mn = 11200, PDI = 2.0). Homopolymerizations of 1,5-cyclooctadiene and norbornene were also studied and resulting polymers were characterized by spectroscopic methods to discuss with copolymers. Glass-transition temperatures of homo- and copolymers were determined by DSC.     

Carbon-13 nuclear magnetic resonance spectra and conformations of cis,cis-1,5-cyclooctadiene monoepoxide and cis,syn,cis-1,5-cyclooctadiene diepoxide

The natural-abundance ¹³C NMR spectra of cis,cis-1,5-cyclooctadiene monoepoxide and cis,syn,cis-1,5-cyclooctadiene diepoxide have been investigated over the temperature range of – 10 to – 180°C. Whereas the spectra of the former showed no dynamic NMR effect, two different conformations in the ratio of 3:1 were observed at low temperatures for the latter. The free-energy barrier (ΔG^≠) for conversion of the major conformation to the minor conformation is calculated to be 5.9°0.2 kcal mol^?1 from a line-shape analysis of spectra obtained at intermediate temperatures. It is shown that cis,syn,cis-1,5-cyclooctadiene diepoxide exists in solution in chair (major) and in twist-boat (minor) conformations of slightly different energies. Interconversion paths between these conformations are discussed. The monoepoxide is suggested to have a twist-boat conformation that is rapidly pseudorotating via a boat conformation even at – 180°C.     

几种光敏剂光敏氧化效率的比较

<正> 光敏氧化效率是由敏化剂分子吸收光量子数及其产生单重态氧的量子产率决定的,这要求敏化剂的吸收光谱同光源的发射光谱很好地匹配。本文报道竹红菌甲素匹配高压钠灯有效地产生单重态氧,高效光敏氧化一系列具有不同反应活性的底物,成为单重态氧化学中一个新的光敏氧化体系。     

Synthesis and Characterization of a Bis(&mgr;-beta-diketonato)bis((1,2,5,6-eta)-1,5-dimethyl-1,5- cyclooctadiene)disilver Complex. An Intermediate in the Synthesis of an Isomerically Pure (beta-Diketonato)((1,2,5,6-eta)-1,5-dimethyl-1,5-cyclooctadiene)copper(I) Complex

Dimethyl-1,5-cyclooctadiene (DMCOD) is synthesized by the Ni-catalyzed dimerization of isoprene and consists of 80% 1,5-dimethyl-1,5-cyclooctadiene (1,5-DMCOD) and 20% 1,6-dimethyl-1,5-cyclooctadiene (1,6-DMCOD). Reaction of Hhfac (1,1,1,5,5,5-hexafluoro-2,4-pentanedione) with Ag(2)O in the presence of DMCOD results in the formation of isomeric Ag(I) species. Repeated recrystallizations yield an isomerically pure compound ((1,5-DMCOD)Ag(hfac))(2) that was characterized by X-ray crystallography and (1)H and (13)C NMR and IR spectroscopy. X-ray crystallography revealed a dinuclear complex with a short Ag-Ag spacing (3.0134(3) ? at -150 degrees C and 3.0278(5) ? at -20 degrees C) and bridging hfac ligands (&mgr;(2) bonding). The overall geometry around the Ag atoms is a deformed tetrahedron with two short Ag-O bonds (2.375 ? average) and two Ag-diene bonds. The methyl groups of the 1,5-DMCOD ligand are pointed toward the center of the molecule. Decomposition of the silver complex in a biphasic HCl (1 M)/CH(2)Cl(2) mixture liberates isomerially pure 1,5-DMCOD; this diene is subsequently used to synthesize isomerically pure (1,5-DMCOD)Cu(hfac). The latter compound was characterized by (1)H and (13)C NMR and IR spectroscopy and is a useful liquid precursor for Cu CVD. Crystallographic data: C(30)H(34)Ag(2)F(12)O(4), monoclinic, P2(1)/c (No. 14), Z = 4; at -150 degrees C, a = 12.428(1) ?, b = 11.071(1) ?, c = 24.520(2) ?, beta = 101.98(1) degrees; at -20 degrees C, a = 12.597(1) ?, b = 11.191(1) ?, c = 24.641(2) ?, beta = 102.08(1) degrees.     

Evidence for a reactive (alkene)peroxoiridium(III) intermediate in the oxidation of an alkene complex with O2

An (alkene)peroxoiridium(III) complex, [Ir(L)(cod)(O(2))] [where LH = PhN=C(NMe(2))NHPh and cod = 1,5-cyclooctadiene], was identified as an intermediate in the reaction of the Ir(I) precursor [Ir(L)(cod)] with O(2) and characterized by spectroscopic methods. Decay of the intermediate and further reaction with 1,5-cyclooctadiene produced 4-cycloocten-1-one.     

Singlet oxygenation of cis,cis-1,5-cyclooctadiene: a convenient synthetic entry into 5,8-difunctionalized oxygen derivatives of 1,3-cyclooctadiene

The 6-hydroperoxy-1,4-cyclooctadiene ($\text{2}$), which is formed in the photosensitized oxygenation of 1,5-cyclooctadiene ($\text{1}$), affords on further singlet oxygenation 5,8-dihydroperoxy-1,3-cyclooctadiene ($\text{3}$), which via triphenylphosphine reduction leads to $\text{cis}$-5,8-dihydroxy-1,3-cyclooctadiene ($\text{4}$) and subsequent pyridinium chlorochromate oxidation to 1,3-cyclooctadien-5,8-dione ($\text{8}$).     

Synthesis of 2,3-disubstituted benzofurans by platinum-olefin-catalyzed carboalkoxylation of o-alkynylphenyl acetals

The PtCl2-catalyzed cyclization reaction of o-alkynylphenyl acetals 1 in the presence of 1,5-cyclooctadiene produces 3-(alpha-alkoxyalkyl)benzofurans 2 in good to high yields. For example, the reaction of acetaldehyde ethyl 2-(1-octynyl)phenyl acetal (1a), acetaldehyde ethyl 2-(cyclohexylethynyl)phenyl acetal (1c), and acetaldehyde ethyl 2-(phenylethynyl)phenyl acetal (1f) in the presence of 2 mol % of platinum(II) chloride and 8 mol % of 1,5-cyclooctadiene in toluene at 30 degrees C gave the corresponding 2,3-disubstituted benzofurans 2a, 2c, and 2f in 91, 94, and 88% yields, respectively.     

Reactions of Trifluoromethylsulfenyl Chloride with 1,5-Cyclooctadiene

The reaction of 1,5-cyclooctadiene with F 3 CSCl at m 80;C has been examined and found to furnish both di- and tetrasubstituted adducts. Their mass spectra show the presence of the intact cyclooctyl ring. However, photolyis of a solution of 1,5-cyclooctadiene and F 3 CSCl in dry pentane yields addition, isomerization and dimerization as well as free radical products. The rationalization of the formation of the above products along with their mass spectral characterization is described in this communication.     

Direct in situ synthesis of cationic N-heterocyclic carbene iridium and rhodium complexes from neat ionic liquid: Application in catalytic dehydrogenation of cyclooctadiene

A direct synthetic route to cationic N-heterocyclic carbene (NHC) complexes of rhodium and iridium from neat dialkyl-imidazolium ionic liquids (ILs) has been found. The method uses complexes bearing basic anionic ligands, [M(COD)(PPh₃)X], X = OEt, MeCO₂, which react with the inactivated imidazolium cation in the absence of external bases yielding one M-NHC moiety and the free protonated base. This new one-pot synthesis leaving pure, catalytically active IL solutions is faster, cleaner and more efficient than traditional syntheses of such NHC complexes. The observed reactivity also gives insight into NHC incorporation of rhodium and iridium catalyzed reactions performed in common dialkyl-imidazolium ILs.The complexes synthesised in this manner are compared with their bis-phosphine analogues in terms of activity for catalytic dehydrogenation of 1,5-cyclooctadiene and 1,3-cyclooctadiene in neat [BMIM][NTf₂] as solvent. Even at high temperature, no ligand exchange reaction is observed with [(COD)M(PPh₃)₂] [NTf₂] catalysts. As expected, the yields of all the reactions were low, iridium was much more active in C-H activation than rhodium and the NHC ligands were more stable than triphenylphosphine. For all catalysts, the isomerisation of 1,5-cyclooctadiene is the major reaction. However, the phosphine-NHC complex of iridium seems to be more selective for dehydrogenation than its bis-phosphine counterpart, which is more active in transfer-hydrogenation and less stable under the applied conditions. Different reaction conditions were tried in order to optimise selectivity for dehydrogenation over isomerisation and transfer-hydrogenation. Surprisingly, with 1,3-cyclooctadiene as substrate selectivity for dehydrogenation is much higher than with 1,5-cyclooctadiene for all catalysts.     

顺, 顺-1,5-环辛二烯的单重态氧反应及其产物的重排

本文报道用竹红菌甲素作光敏剂匹配高压钠灯光源, 对1,5-环辛二烯(1)进行单重态氧氧化反应, 高产率和立体选择性地得到顺-5,8-二(氢过氧基)-1,3-环辛二烯(7). 证明了7还原产物顺-5,8-二烃基-1,3-环辛二烯(8)热重排的产物是6-羟基-4-环辛烯酮(3). 而不是6-羟基-3-环辛烯酮(6). 并讨论了热重排过程的机理.     

Rhodium and iridium complexes of N-heterocyclic carbenes: Structural investigations and their catalytic properties in the borylation reaction

Bridged and unbridged N-heterocyclic carbene (NHC) ligands are metalated with [Ir/Rh(COD)₂Cl]₂ to give rhodium(I/III) and iridium(I) mono- and biscarbene substituted complexes. All complexes were characterized by spectroscopy, in addition [Ir(COD)(NHC)₂][Cl,I] [COD = 1,5-cyclooctadiene, NHC =  1,3-dimethyl- or 1,3-dicyclohexylimidazolin-2-ylidene] (1, 4), and the biscarbene chelate complexes 12 [(η⁴-1,5-cyclooctadiene)(1,1′-di-n-butyl-3,3′-ethylene-diimidazolin-2,2′-diylidene)iridium(I) bromide] and 14 [(η⁴-1,5-cyclooctadiene)(1,1′-dimethyl-3,3′-o-xylylene-diimidazolin-2,2′-diylidene)iridium(I) bromide] were characterized by single crystal X-ray analysis. The relative σ-donor/π-acceptor qualities of various NHC ligands were examined and classified in monosubstituted NHC-Rh and NHC-Ir dicarbonyl complexes by means of IR spectroscopy. For the first time, bis(carbene) substituted iridium complexes were used as catalysts in the synthesis of arylboronic acids starting from pinacolborane and arene derivatives.     

High temperature pyrolysis of 1,5-cyclooctadiene and 4-vinylcyclohexene in shock waves

1,5-cyclooctadiene or 4-vinylcyclohexene mixture diluted with argon was heated to temperatures in the range 880–1230 K behind reflected shock waves. Profiles of IR-laser absorption were measured at 3.39 μm. From these profiles, rate constants k₁ and k₂ for the decyclization reactions 1,5-cyclooctadiene → biradical and 4-vinylcyclohexene → biradical were evaluated as k₁ = 5.2 × 10¹⁴ exp(?48.3 kcal/RT) s^?1 and k₂ = 3.5 × 10¹⁴ exp(?55.3 kcal/RT) s^?1, respectively. © 1993 John Wiley & Sons, Inc.     

Dimerization of vinylcyclopropane and its codimerization with 1,3-dienes catalyzed by cobalt complexes

Conclusions The dimerization of vinylcyclopropane to 2-cyclopropyl-1,5(Z)-heptadiene and the codimerization of vinylcyclopropane with 1,3-dienes (butadiene, isoprene, and 2-cyclopropylbutadiene) with the formation of 2-cyclopropyl-1,4-hexadienes were carried out in the presence of the catalytic systems Co(acac)₃-1,2-bis(diphenylphosphino)ethane [1,2-bis(diphenylphosphino)methane]-AlEt₂Cl.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1356–1360, June, 1988.     

Synthesis of alicyclic derivatives of spiropentane based on 1,5-cyclooctadiene

Methods for the synthesis of alicyclic derivatives f spiropentane by ]1 +2] cycloaddition of halo- and dihalocarbenes to 1,5-cyclooctadiene followed by dehydrohalogenation and cyclopropanation of the olefins formed are described.Translated fromIzvestiya Akademii Nauk Seriya Khimicheskaya No. 7, no, 1753–1757 July 1996.     

(E,E)-1,5-Cyclooctadiene: a small and fast click-chemistry multitalent

Two in one--We show here that the highly strained trans,trans-diolefin (E,E)-1,5-cyclooctadiene can perform efficiently two different click reactions at fast reaction rates. It is capable of first undergoing [3+2] cycloadditions with 1,3-dipoles at a reaction rate comparable to that of strained cyclooctynes. The resulting cycloadduct can then perform a much faster inverse-electron-demand Diels-Alder reaction with tetrazines, effectively linking an azide to a tetrazine. Thus, (E,E)-1,5-cyclooctadiene could have many applications in chemical biology and polymer chemistry.     

Ring synthesis by stereoselective, methylene-free enyne cross metathesis

Tandem enyne metathesis between 1-alkynes and 1,5-cyclooctadiene or all-cis-1,4-polybutadiene resulted in a direct, one-step ring synthesis of cyclohexadienes by methylene-free metathesis. The use of methylene-free metathesis conditions provided apparent Z-selectivity in the intermolecular enyne metathesis step.     

磷化氢与环烯烃反应的原位^3^1P NMR研究

本文应用加压原位核磁共振波谱技术, 在反应温度50-70℃、反应压力1.0-2.0MPa, 氘代苯为溶剂, 偶氮二异丁腈为引发剂的条件下, 考察了磷化氢与环烯烃1, 5-环辛二烯、双环戊二烯、1, 3-环己二烯、1, 4-环己二烯及1, 5, 9-环十二三烯的反应。实验结果表明, 磷化氢与1, 5-环辛二烯反应主要生成双环膦杂环壬烷; 与其它环烯烃均不生成膦杂环化合物, 仅为一取代伯膦或二取代仲膦产物。磷化氢与环烯烃反应仍为串行机理。     

Heteronuklear überbrückte tricyclische Systeme. Oxa-brexane- und -brendane

Unsaturated cyclic and bicyclic hydrocarbons react with chloral in presence of aluminium chloride to yield tricyclic oxabrexanes which undergo acid catalyzed rearrangements to oxabrendanes. 1,5-cyclooctadiene gives the new oxa-cyclo[c, d]octahydropentalen. Structural evaluations and stereochemical assignments are discussed on the basis of detailed ¹H- and ¹³C-NMR.-spectra.