1119-51-3Relevant articles and documents
Cobalt-Mediated η5-Pentadienyl/Alkyne [5 + 2] Cycloaddition Reactions: Substitution Effects, Bicyclic Synthesis, and Photochemical η4-Cycloheptadiene Demetalation
Ylijoki, Kai E. O.,Kirk, Andrew D.,B?cklein, Sebastian,Witherell, Ross D.,Stryker, Jeffrey M.
, p. 3335 - 3357 (2015)
The preparation of seven-membered carbocycles via traditional organic synthesis is difficult, yet essential, due to the prevalence of these moieties in bioactive compounds. As we report, the Co-mediated pentadienyl/alkyne [5 + 2] cycloaddition reaction generates kinetically stable η2,η3-cycloheptadienyl complexes in high yield at room temperature, which isomerize to the thermodynamically preferred η5-cycloheptadienyl complexes upon heating at 60-70 °C. Here we describe an extended investigation of this reaction manifold, exploring substituent effects and extending the reaction to tandem cycloaddition/nucleophilic cyclizations, generating fused bicyclic compounds. We also describe a new high-yielding photolytic method for the decomplexation of organic cycloheptadienes from Co(I) complexes. Both C5Me5 (Cp?) and C5H5 (Cp) half-sandwich complexes are active in [5 + 2] cycloaddition with alkynes, with Cp? generally providing higher yields of cycloheptadienyl complexes. Cp cycloheptadienyl complexes, however, are resistant to thermal η2,η3 ' η5 isomerization. The reaction remains limited to open pentadienyl complexes incorporating substituents in the terminal (1 and 5) positions, except for the unsubstituted CpCo(η5-cycloheptadienyl)+ complex, which is modestly reactive. Incorporation of tethered latent nucleophiles allows cyclization onto the intermediate cycloheptadienyl cations, producing bicyclo[5.3.0]decadiene and bicyclo[5.4.0]undecadiene systems with complete diastereocontrol. A selection of intermediate complexes have been crystallographically characterized. Addition of tethered malonate nucleophiles occurs reversibly with equilibration to a thermodynamic elimination product, while enolate nucleophiles cyclize reliably under kinetic control. The resulting bicyclic products are decomplexed in high (>90%) yield by UV photolysis in the presence of allyl bromide to provide the organic bicyclic diene with complete retention of ring fusion geometry and without double-bond isomerization.
An original synthesis of highly ordered organosilica with a high content of thiol groups
Alauzun, Johan,Mehdi, Ahmad,Reye, Catherine,Corriu, Robert J. P.
, p. 347 - 349 (2006)
Well ordered bridged organosilica highly functionalised with disulfide groups were obtained by self-assembly of α,ω-bis(trimethoxysilyl) alkyldisulfide under hydrophilic conditions; the reduction of disulfide cores to SH groups gave rise to material having a high mercury ion adsorption capacity. The Royal Society of Chemistry 2006.
Phospho-Cope Rearrangement of Sodium Allylvinylphosphinate
Loewus, David I.
, p. 2292 - 2296 (1981)
Sodium allylvinylphosphinate (1) rearranges thermally to sodium hydrogen pent-4-enephosphonate (3) in virtually quantitative yield.The reaction probably constitutes a phospho-Cope rearrangement and presumably proceeds by way of the monomeric metaphosphonate 2 as a reactive intermediate.The half-time for the reaction is 4.67 h in water at 193.6+/- 1.0 deg C and 6.03 h in ethanol.By contrast, ethyl allylvinylphosphinate reacts in ethanol to give a mixture of compounds; although some of the product expected for a phospho-Cope is present in the mixture, the rearrangement is slower than that of the anion by a factor of at least 16.The mechanistic implications of these facts are discussed.
Dimethylamine as a Substrate in Hydroaminoalkylation Reactions
Bielefeld, Jens,Doye, Sven
, p. 15155 - 15158 (2017)
Transition-metal-catalyzed hydroaminoalkylations of alkenes have made great progress over the last decade and are heading to become a viable alternative to the industrial synthesis of amines through hydroformylation of alkenes and subsequent reductive amination. In the past, one major obstacle of this progress has been an inability to apply these reactions to the most important amines, methylamine and dimethylamine. Herein, we report the first successful use of dimethylamine in catalytic hydroaminoalkylations of alkenes with good yields. We also report applicability for a variety of alkenes to show the tolerance of the reaction towards different functional groups. Additionally, we present a catalytic dihydroaminoalkylation reaction using dimethylamine, which has never been reported before.
Simple and high yield access to octafunctional azido, amine and urea group bearing cubic spherosilicates
Sch?fer, Sandra,Kickelbick, Guido
, p. 221 - 226 (2017)
Spherosilicates and polyhedral oligomeric silsesquioxanes represent unique well-defined rigid building blocks for molecular and hybrid materials. Drawbacks in their synthesis are often low yields and the restricted presence of functional groups either based on incomplete transformation of all corners or the reactivity of the functional groups. Particularly amine-functionalization reveals some synthetic challenges. In this study we report the synthesis of a new class of octafunctionalized hydrogen bond forming spherosilicates via a facile route based on octabromo alkyl functionalized cubic spherosilicates. Four different alkyl chain lengths, namely C4, C5, C6 and C11, were realized starting from ω-alkenylbromides via hydrosilylation of Q8M8H. Using sodium azide in a mixture of acetonitrile:DMF = 10:1, the octaazide was obtained quantitatively and could be rapidly transformed in an octaamine cube via catalytic hydrogenation over Pd/C in absolute ethanol. The following reaction to hydrogen bond forming spherosilicates was performed in situ by adding propyl isocyanate. All transformations proceed quantitatively at the eight corners of the cube, which was evidenced by NMR spectroscopy and ESI-MS measurements. The Q8-target compound can be separated after each reaction step over simple chemical workup while no cage rearrangement was observed. The structures were confirmed using 1H, 13C, 29Si-NMR, FT-IR, elemental analysis and ESI-MS. The method opens a high yield route (overall isolated yield 83-88%) for structural building blocks in hybrid materials.
Further Studies of Substitution Reactions of Stannyl and Germyl Anionoids with Alkyl Bromides. Rearrangement of the 6-Hepten-2-yl Moiety
Kitching, William,Olszowy, Henry A.,Harvey, Karen
, p. 1893 - 1904 (1982)
The stereochemical outcomes of reactions of (trimethyltin)lithium, (dimethylphenyltin)lithium, (methyldiphenyltin)lithium, and (triphenyltin)lithium in tetrahydrofuran with trans- and cis-2-,3-, and 4-methylcyclohexyl bromides have been determined on the basis of 1H and 13C NMR spectroscopy.The (C6H5)3SnLi reactions proceed stereospecifically with inversion at carbon, while the (CH3)3SnLi reactions are nonstereospecific, as observed previously in some other systems. cis- and trans-2-methoxybromocyclohexanes and -cyclopentanes were also reacted with (CH3)3SnLi, and lowyields of (2-methoxycyclohexyl)- and (2-methoxycyclopentyl)trimethylstannanes were isolated.On the basis of 13C NMR spectra and deoxystannylation reactions , the former is largely ( 90percent) trans while the latter is exlusively trans.The pronounced stereochemical distinction between reactions of (CH3)3SnLi and (C6H5)3SnLi with cyclohexyl bromides is not observed in corresponding reactions of (CH3)3GeLi and (C6H5)3GeLi; both are nonspecific.Certain reactions of cyclopropylcarbinyl bromide and 6-bromo-1-hexene with R3SnLi and R3GeLi (R=CH3 or C6H5) were also studied.Rearranged product (allylcarbinyl) was observed in the reaction of cyclopropylcarbinyl bromide with (CH3)3SnLi, but cyclopentylmethyl products (from cyclization of any hex-5-enyl free radical) was not observed in any case.However, with the secondary 6-bromo-1-heptene all reagents studied (with the exception of (C6H5)3SnLi) afforded rearranged (2-methylcyclopentyl)methyl products, consistent with the intervention of the free radical, wich cyclizes rapidly.Some further estimates of the conformational A values of R3Ge and R3Sn are reported, and triphenyl derivatives have significantly larger values.
Synthesis of 1,10-dimethylbicyclo[8.8.8]hexacosane and 1,10- dihydroxybicyclo[8.8.8]hexacosane
Jones, Ian W.,Monguchi, Yasunari,Dawson, Alice,Carducci, Michael D.,Mash, Eugene A.
, p. 2841 - 2843 (2005)
(Chemical Equation Presented) 1,10-Dimethylbicyclo[8.8.8]hexacosane (1) and 1,10-dihydroxybicyclo[8.8.8]hexacosane (2) were prepared in 4% yield over seven steps and in 18% yield over three steps, respectively, starting from 1,10-cyclooctadecanedione. The identities and out,out conformations of these compounds were established by single-crystal X-ray analysis.
The facile preparation of alkenyl metathesis synthons
Baughman, Travis W.,Sworen, John C.,Wagener, Kenneth B.
, p. 10943 - 10948 (2004)
We report synthetic methodology allowing the preparation of any length alkenyl halide from inexpensive starting reagents. Standard organic transformations were used to prepare straight chain α-olefin halides in excellent overall yields with no detectable olefin isomerization and full recovery of any unreacted starting material. Reported transformations can be used for the selective incorporation of pure α-olefin metathesis sites in highly functionalized molecules.
Novel synthetic method 5 -bromo -1 - pentene (by machine translation)
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Paragraph 0021; 0031-0042, (2020/06/30)
N, N - dimethylformamide is used as a starting raw material, N, N-dimethylformamide is used as a solvent and is heated; 5 - bromo -1 - pentene crude product is obtained by reaction of hexamethylphosphoric acid triamine as a catalyst; crude product is washed twice with brine; and high-purity 1,5 - bromo -1 -1 - 5 - pentene is obtained by rectification 5 . To the method, the existing synthesis process and post-treatment are simplified, the reaction yield is improved, the production stability is improved, and the production cost is reduced. (by machine translation)
Formal Bromine Atom Transfer Radical Addition of Nonactivated Bromoalkanes Using Photoredox Gold Catalysis
Zidan, Montserrat,McCallum, Terry,Swann, Rowan,Barriault, Louis
supporting information, p. 8401 - 8406 (2020/11/03)
Organic transformations mediated by photoredox catalysis have been at the forefront of reaction discovery. Recently, it has been demonstrated that binuclear Au(I) bisphosphine complexes, such as [Au2(μ-dppm)2]X2, are capable of mediating electron transfer to nonactivated bromoalkanes for the generation of a variety of alkyl radicals. The transfer reactions of bromine, derived from nonactivated bromoalkanes, are largely unknown. Therefore, we propose that unique metal-based mechanistic pathways are at play, as this binuclear gold catalyst has been known to produce Au(III) Lewis acid intermediates. The scope and proposed mechanistic overview for the formal bromine atom transfer reaction of nonactivated bromoalkanes mediated by photoredox Au(I) catalysis is presented. The methodology presented afforded good yields and a broad scope which include examples using bromoalkanes and iodoarenes.
