- Cobalt-Mediated η5-Pentadienyl/Alkyne [5 + 2] Cycloaddition Reactions: Substitution Effects, Bicyclic Synthesis, and Photochemical η4-Cycloheptadiene Demetalation
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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.
- Ylijoki, Kai E. O.,Kirk, Andrew D.,B?cklein, Sebastian,Witherell, Ross D.,Stryker, Jeffrey M.
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- An original synthesis of highly ordered organosilica with a high content of thiol groups
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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.
- Alauzun, Johan,Mehdi, Ahmad,Reye, Catherine,Corriu, Robert J. P.
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- Phospho-Cope Rearrangement of Sodium Allylvinylphosphinate
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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.
- Loewus, David I.
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- Dimethylamine as a Substrate in Hydroaminoalkylation Reactions
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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.
- Bielefeld, Jens,Doye, Sven
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- Simple and high yield access to octafunctional azido, amine and urea group bearing cubic spherosilicates
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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.
- Sch?fer, Sandra,Kickelbick, Guido
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- Further Studies of Substitution Reactions of Stannyl and Germyl Anionoids with Alkyl Bromides. Rearrangement of the 6-Hepten-2-yl Moiety
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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.
- Kitching, William,Olszowy, Henry A.,Harvey, Karen
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- Synthesis of 1,10-dimethylbicyclo[8.8.8]hexacosane and 1,10- dihydroxybicyclo[8.8.8]hexacosane
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(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.
- Jones, Ian W.,Monguchi, Yasunari,Dawson, Alice,Carducci, Michael D.,Mash, Eugene A.
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- The facile preparation of alkenyl metathesis synthons
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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.
- Baughman, Travis W.,Sworen, John C.,Wagener, Kenneth B.
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- Formal Bromine Atom Transfer Radical Addition of Nonactivated Bromoalkanes Using Photoredox Gold Catalysis
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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.
- Zidan, Montserrat,McCallum, Terry,Swann, Rowan,Barriault, Louis
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supporting information
p. 8401 - 8406
(2020/11/03)
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- Novel synthetic method 5 -bromo -1 - pentene (by machine translation)
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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)
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Paragraph 0021; 0031-0042
(2020/06/30)
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- ADMET Polymers Containing Precisely Spaced Pendant Boronic Acids and Esters
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Precise aryl boronic ester- and acid-containing polymers have been synthesized via acyclic diene metathesis. High-molecular weight phenyl boronic acid polymers were synthesized. Cross-linked phenyl boronic acid polymers were also synthesized and demonstrate a unique crystallization behavior not usually seen in cross-linked polymers. (Graph Presented).
- Simocko, Chester,Young, Thomas C.,Wagener, Kenneth B.
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p. 5470 - 5473
(2015/09/02)
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- Cooperative catalysis with aldehydes and copper: Development and application in aerobic oxidative C-H amination at room temperature
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A conceptually new cooperative catalytic system via a synergistic combination of aldehyde and copper catalysis has been established based on systemic mechanistic studies. This new cooperative catalysis has been successfully applied in the direct aerobic oxidative C-H amination of azoles at room temperature, which was previously realized under harsh conditions. Mechanistic studies including isotopic labeling experiments and kinetic isotope effect (KIE) experiments support a reaction pathway that involves formation of an aminal, hydrolysis of the aminal to generate the copper-amide species, subsequent C-H amination and re-oxidation of copper(I) to copper(II) by oxygen. It not only provides an efficient method to realize the oxidative C-H amination of benzoxazoles with free amines at room temperature, but also paves the way for establishing new C-N bond formation reactions by using this efficient cooperative catalysis. Copyright
- Xie, Yinjun,Qian, Bo,Xie, Pan,Huang, Hanmin
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supporting information
p. 1315 - 1322
(2013/06/27)
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- Low catalyst loading in ring-closing metathesis reactions
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An efficient procedure is described for ring-closing metathesis reactions. A conversion of 95 % for diethyl diallylmalonate in dilute solution could be achieved within a few minutes, reaching TOF=4173min-1, with very low loading of commercially available Ru catalysts that contained unsaturated NHC ligands. In general, only 50 to 250ppm of the catalyst is required to achieve near-quantitative conversion into a broad variety of 5-16-membered heterocyclic compounds. The practicality of this procedure was illustrated in the synthesis of 5-8-membered N-tert-butoxycarbonyl (N-Boc)- and N-para-toluenesulfonyl (N-Ts)-protected cyclic amines and 9-16-membered lactones. The synthesis of macrocyclic proline-based lactams required slightly higher catalyst loadings. Along with monocyclic products, oligomeric byproducts, mostly cyclodimers, were isolated and characterized. Getting some closure: An efficient procedure is described for ring-closing metathesis reactions in which only 50 to 250ppm of catalyst is required to effect almost-quantitative conversion into a broad range of 5-16-membered heterocyclic compounds. The practicality of this procedure was illustrated in the synthesis of 5-8-membered N-protected cyclic amines, 9-16-membered lactones, and 11-16-membered proline-based lactams. Copyright
- Kadyrov, Renat
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supporting information
p. 1002 - 1012
(2013/02/23)
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- Carbocationic n-endo-trig cyclizations
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Unsaturated benzyl cations (4-MeOC6H4)CH +-(CH2)n-CH=CH2 (1) have been generated laser-flash photolytically in acetonitrile in the presence of enol ethers or 2-methylfuran. The reactions of the cations 1 (n = 2 and 4) with these π-nucleophiles follow second-order rate laws with rate constants comparable to those of the analogous saturated species (4MeOC6H 4)CH+-(CH2)3CH3. Product studies show the absence of cyclization products. In contrast, the carbocation (4-MeOC6H4)CH+-(CH2) 3-CH=CH2 (Id) undergoes a highly reversible 6endo-trig cyclization which is approximately 107 times faster than the corresponding intermolecular reaction of (4MeOC6H4)CH +-(CH2)3CH3 with hex1-ene. This cyclization yields a highly electrophilic, partially bridged carbocation, which accounts for the finding that Id is consumed eight times faster in trifluoroethanol solution than all other carbocations of this series. Quantum-chemical calculations (B3LYP/6311G(d,p) and MP2/6-31+G(2d,p)) have been performed to elucidate the structures of the involved carbocations. Consequences of these findings on the role of π-participation in solvolysis reactions are discussed.
- Shi, Lei,Horn, Markus,Kobayashi, Shinjiro,Mayr, Herbert
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supporting information; experimental part
p. 8533 - 8541
(2010/03/26)
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- Synthesis of 2-arylcycloalka-2,4-dienones using sulfone-based methodology
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Addition of the anion derived from (phenylthiomethyl)phenyl sulfone to a selection of aryl ω-alkenyl ketones gives adducts that via a sequence of Lewis acid catalyzed rearrangement, α-allylation, and metathesis give rise to 2-thio-4-cycloalkenones. These in turn give cycloalkadienones upon oxidation and elimination. An attempt to develop a polymer-supported variant fails because of the reversibility of sulfone anion addition.
- Hok, Saphon,Schore, Neil E.
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p. 1736 - 1738
(2007/10/03)
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- Facially controlled C-methylation of oxolanyl and cyclopentyl acetate enolates: Application to the total synthesis of (+)-nephromopsinic acid
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The stereoselectivity of the C-methylation of oxolanyl and cyclopentyl acetate enolates 5a-22a was investigated. The configuration of the C-methyl diastereomers was elucidated by a combination of crystal structure analysis, NMR spectroscopy and chemical correlations. Generally, the methylation proceeded re*-selectively, although with very different degrees of selectivity. The most important stereodirecting effect was a steric one exerted by the 5-phenethyl substituent, and this steric effect was strongly increased by the stereodirecting effect of a 3-OR group. Contrary to previous literature evidence, the endocyclic oxolanyl oxygen does not exert an effect. These findings were applied in a highly stereoselective synthesis of (+)-nephromopsinic acid (94). Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005.
- Mulzer, Johann,Steffen, Ulrich,Martin, Harry J.,Zorn, Ludwig
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p. 1028 - 1043
(2007/10/03)
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- One-pot synthesis of aryl sulfones from alcohols
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A one-pot synthesis of aryl sulfones from primary alcohols is described. Alcohols were treated with N-bromosuccinimide and triphenylphosphine, followed by addition of sodium arenesulfinate with a catalytic amount of tetrabutylammonium iodide to afford the aryl sulfones in good to high yields.
- Murakami, Teiichi,Furusawa, Kiyotaka
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p. 479 - 482
(2007/10/03)
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- Synthesis of racemic 8-nonene-2,4-diol, acyclic precursor of 1,3-dimethyl-1,9-dioxabicyclo[3.1.1]nonane
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A new way of synthesis was developed for racemic 8-nonene-2,4-diol, the acyclic precursor of 1,3-dimethyl-1,9-dioxabicyclo[3.1.1]nonane. The latter substance was isolated from the bark of an ordinary spruce affected with a pest Trypodendron Lineatum Oliv.
- Vakhidov,Shakhmaev,Ishmuratov,Zorin
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p. 771 - 773
(2007/10/03)
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- Synthesis of (Z)-6-heneicosen-11-one, (+/-)(Z)-14-methyl-8-hexadecen-1-ol and (+/-)-5,6-dehydrosenedigitalene
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Three naturally occurring compounds (Z)-6-heneicosen-11-one (1), (+/-)-(Z)-14-methyl-8-hexadecen-1-ol (2) and (+/-)-5,6-dehydrosenedigitalene (3) have been synthesised using lithium tetrachlorocuperate catalysed coupling reaction.
- Sharma, M. L.,Verma, Sadhana,Chand, Tek
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p. 1030 - 1034
(2007/10/03)
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- Intramolecular Carbometallation of Organozinc Reagents
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The intramolecular cyclization reaction of primary or secondary alkenylzincs leads to a cyclopentylmethylzinc derivatives in a totally regiospecific 5-exo-trig cyclization in the presence of a highly sensitive function.
- Meyer, Christophe,Marek, Ilane,Courtemanche, Gilles,Normant, Jean-F.
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p. 11665 - 11692
(2007/10/02)
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- INSECT PHEROMONES AND THEIR ANALOGS. XLVII. SYNTHESIS OF 11-OXODODECA-3,6-DIYNOIC ACID - THE ACYCLIC PRECURSOR OF A MACROLIDE COMPONENT OF PHEROMONES OF Oryzaephilus mercator AND O. surinamensis
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A new approach is proposed to the synthesis of 11-oxododeca-3,6-diynoic acid - the acyclic precursor of a macrolide component of pheromones of Oryzaephilus mercator and O. surinamensis - from the readily available tetrahydropyran or allylacetone via the intermediate 5-bromo-2,2-ethylenedioxypentane.
- Odinokov, V. N.,Ishmuratov, G. Yu.,Kharisova, R. Ya.,Vakhidov, R. R.,Botsman, L. P.,Tolstikov, G. A.
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p. 240 - 244
(2007/10/02)
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- Photoreactions of Enones with Amines - Cyclization of Unsaturated Enones and Reductive Ring Opening by Photoinduced Electron Transfer (PET)
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Photolysis of the unsaturated enones 1 yields cycloaddition products 2 and 3 with varying regioselectivity.Under electron transfer conditions (PET) spirocyclic products 4 are formed.The straight cycloaddition products 2b, c, f are converted to the spirocyclic products 4b, c, f under the same reaction conditions.The cyclobutane 5 and cyclopropane 11 also undergo this new reductive ring opening reaction, while the stabilized system 7 is converted to reduced ring-enlarged triquinane 10 which may be interesting in natural product synthesis. - Irradiation of 2-cyclohexen-1-one (14) in the presence of N,N-dimethylallylamine (15) leads to the decahydroisoquinoline 18.A mechanism involving radical intermediates is discussed. Key Words: Photoinduced electron transfer / Cyclization / Ring opening / Enones
- Mattay, Jochen,Banning, Anja,Bischof, Eric W.,Heidbreder, Andreas,Runsink, Jan
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p. 2119 - 2128
(2007/10/02)
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- Solvolysis Rates and β-Deuterium Secondary Kinetic Isotope Effects of Some Tertiary and Secondary Alk-5-enyl Derivatives. Evidence for ?-Participation
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Tertiary 1,1-dimethylalk-5-enyl chlorides solvolyze in 80percent v/v ethanol with no or moderate rate enhancements attributable to ?-participation.However, secondary β-deuterium kinetic isotope effects (KIE, two deuterated methyl groups) are significantly reduced (kH/kD = 1.22-1.57) relative to the saturated analogues (kH/kD = 1.80), indicating participation of the double bond.Secondary 1-methylalk-5-enyl tosylates show the same trends, i.e., no or very moderate rate enhancements but reduced β-deuterium secondary KIE relative to the saturated analogue.
- Orlovic, Mirko,Borcic, Stanko,Humski, Kresimir,Kronja, Olga,Imper, Vera,et al.
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p. 1874 - 1878
(2007/10/02)
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- Novel Bicyclization of Enynes and Diynes Promoted by Zirconocene Derivatives and Conversion of Zirconabicycles into Bicyclic Enones via Carbonylation
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Enynes and diynes react with "ZrCp2" (where Cp = η5-C5H5) generated by treating Cl2ZrCp2 with Mg and HgCl2 or 2 equiv of an alkyllithium, such as n-BuLi, or a Grignard reagent, such as EtMgBr, and can produce in excellent yields zirconabicycles represented by 2 (M = Zr) and 8, respectively.Their protonolysis can provide the corresponding exocyclic alkenes and conjugated dienes 9, respectively.Iodinolysis of 2 (M = Zr) can give the corresponding diiodides in high yields, while carbonylation of 2 (M = Zr) can produce bicyclic enones 3 (Y = O) in moderate to goodyields.Although the bicyclization reaction fails with terminal alkyne containing substrates, various types of substituents on the alkyne moiety, such as alkyl, alkenyl, aryl, trialkylsilyl, and trialkylstannyl groups, can be accommodated.Investigation of the n-BuLi-Cl2ZrCp2 reaction has revealed that is gives first (n-Bu)2ZrCp2 at -78 deg C, which then decomposes to give Cp2Zr(CH2=CHEt), identified as its PMe3 complex 11.The PMe3-stabilized complex reacts with diphenylacetylene to produce a crystalline compound which has been identified as a zirconacyclopropene, 36a.This demonstrated, for the first time, the feasibility of converting alkynes into zirconacyclopropenes.The reaction of preformed, three-membered zirconacycles with alkynes gives five-membered zirconacycles.The reaction of diphenylacetylene is ca. 150 times as fast as that of (E)-stilbene.These results support a mechanism involving formation of a zirconacyclopropene intermediate followed by its intramolecular carbometalation with the alkene moiety of enynes for the Zr-promoted bicyclization of enynes.
- Negishi, Ei-ichi,Holmes, Steven J.,Tour, James M.,Miller, Joseph A.,Cederbaum, Fredrik E.,et al.
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p. 3336 - 3346
(2007/10/02)
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- Characteristic odoriferous compounds of brown algae: Syntheses of possible oxidation products of (6Z,9Z,12Z,15Z)-1,6,9,12,15-heneicosapentaene and (6Z,9Z,12Z,15Z,18Z)-1,6,9,12,15,18-heneicosahexaene
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The unsaturated aldehydes (3Z,6Z)-3,6,11-dodecatrienal (9), (2E,4Z,7Z)-2,4,7,12-tridecatetraenal (10) and (3Z,6Z,9Z)-3,6,9,14-pentadecatetraenal (11) are expected to be products of the air oxidation of heneicosapentaene 1 and heneicosahexaene 2.The first attempts to synthesize aldehydes 9 and 11 (which failed) were based upon repeated Horner-Wittig reactions with phosphine oxide 12.In a second attempt, acetylene chemistry was applied to prepare aldehydes 9, 10 and 11.Their olfactive properties are described.
- Broekhof, Nico L.J.M.,Witteveen, Jan G.,Weerdt, Anton J. A. van der
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p. 436 - 442
(2007/10/02)
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- INTRAMOLECULAR ALKYLATION OF CYCLOPENTENONES: A GENERAL ROUTE TO CONJOINT RING SYSTEMS
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The intramolecular alkylation of several bromo- and epoxy-2-methylcyclopentenones, 18-23 and 33, are described.In all cases, except 33, alkylative cyclization occours at the γ' position to the conjoint ring systems 25-31.The "blocked" bromide 33 (γ' geminal dimethyl substituent) cyclizes to the fused ring hydrindenones 35 and/or 34 depending upon conditions.Enolate anion generation from 3-ethyl-2-methyl-2-cyclopentenone (36) with various bases (KH, LDA, Et3N) is described and the anion populations determined by quenching with chlorotrimethylsilane to afford the enol ethers 39-41.The intramolecular alkylations are discussed.
- Antczak, Kazimierz,Kingston, John F.,Alward, Sandra J.,Fallis, Alex G.
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p. 829 - 837
(2007/10/02)
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- A New Synthesis of (E)-3,7-Dimethyloct-2-en-1,8-diol, a Component of the Hairpencil Secretion of African Monarch Butterfly
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A facile synthesis of the title compound (1) has been achieved.The key intermediate, viz, the keto acid (6) is prepared via a novel route starting from the alkenol (2).Bromination of (2), and subsequent elaboration through the alkylation of diethyl malonate or propionic acid, affords the alkenoic acid (5) which upon oxidation with Jones' reagent in presence of Hg(OAc)2, provides 6.Following a well-established sequence of reactions, 6 is then transformed into 1.
- Joshi, N..N.,Mamdapur, V. R.,Chadha, M. S.
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p. 238 - 240
(2007/10/02)
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