- Synthesis of (polyfluoroalkyl)cyclopentenes as model compounds for fluorophilic cyclopentadienes
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Nucleophilic opening of the epoxide ring in 6-oxabicyclo[3.1.0]hexane (1) with ethenyl-magnesium bromide was employed for the preparation of 2-ethenylcyclopentan-1-ol (2). Radical addition of perfluoroalkyl iodides 3 to alcohol 2 afforded (polyfluoroiodoalkyl)cyclopentanols 4, which were deiodinated with tributylstannane to (polyfluoroalkyl)-cyclopentanols 5, followed by dehydration with Nafion-H to the target (polyfluoroalkyl)-cyclopentenes 6, which are potential intermediates for fluorous chemistry. Attempts to synthesize (polyfluoroalkyl)cyclopentadienes or bis(polyfluoroalkyl)cyclopentadienes failed due to the exclusive formation of unexpected side product, polyfluoroiodoalkanol 7, in the course of radical addition of perfluoroalkyl iodides 3 to ethenylcyclopentenol (8) or diethenylcyclopentanediol (9), respectively.
- Kvicala, Jaroslav,Briza, Tomas,Paleta, Oldrich,Cermak, Jan
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- Photoinduced Cross-Coupling of Aryl Iodides with Alkenes
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A protocol for photoinduced cross-coupling of aryl iodides having polar π-functional groups or elongated π-conjugation with alkenes has been developed. The radical cascade mechanism involving generation of aryl radicals via C-I bond homolysis of photoexcited aryl iodides and their subsequent addition to alkenes is proposed. The method enables iodide-selective cross-coupling over other halogen leaving groups with functional group compatibility on both arene and alkene motifs.
- Liu, Yuliang,Li, Haoyu,Chiba, Shunsuke
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supporting information
p. 427 - 432
(2021/01/26)
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- Accessing Frustrated Lewis Pair Chemistry through Robust Gold@N-Doped Carbon for Selective Hydrogenation of Alkynes
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Pyrolysis of Au(OAc)3 in the presence of 1,10-phenanthroline over TiO2 furnishes a highly active and selective Au nanoparticle (NP) catalyst embedded in a nitrogen-doped carbon support, Au@N-doped carbon/TiO2 catalyst. Parameters such as pyrolysis temperature, type of support, and nitrogen ligands as well as Au/ligand molar ratios were systematically investigated. Highly selective hydrogenation of numerous structurally diverse alkynes proceeded in moderate to excellent yield under mild conditions. The high selectivity toward the industrially important alkene substrates, functional group tolerance, and the high recyclability makes the catalytic system unique. Both high activity and selectivity are correlated with a frustrated Lewis pairs interface formed by the combination of gold and nitrogen atoms of N-doped carbon that, according to density functional theory calculations, can serve as a basic site to promote the heterolytic activation of H2 under very mild conditions. This "fully heterogeneous" and recyclable gold catalyst makes the selective hydrogenation process environmentally and economically attractive.
- Fiorio, Jhonatan Luiz,Gon?alves, Renato Vitalino,Teixeira-Neto, Erico,Ortu?o, Manuel A.,López, Núria,Rossi, Liane Marcia
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p. 3516 - 3524
(2018/04/14)
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- Gold-Ligand-Catalyzed Selective Hydrogenation of Alkynes into cis-Alkenes via H2 Heterolytic Activation by Frustrated Lewis Pairs
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The selective hydrogenation of alkynes to alkenes is an important synthetic process in the chemical industry. It is commonly accomplished using palladium catalysts that contain surface modifiers, such as lead and silver. Here we report that the adsorption of nitrogen-containing bases on gold nanoparticles results in a frustrated Lewis pair interface that activates H2 heterolytically, allowing an unexpectedly high hydrogenation activity. The so-formed tight-ion pair can be selectively transferred to an alkyne, leading to a cis isomer; this behavior is controlled by electrostatic interactions. Activity correlates with H2 dissociation energy, which depends on the basicity of the ligand and its reorganization on activation of hydrogen. High surface occupation and strong Au atom-ligand interactions might affect the accessibility and stability of the active site, making the activity prediction a multiparameter function. The promotional effect found for nitrogen-containing bases with two heteroatoms was mechanistically described as a strategy to boost gold activity. (Graph Presented).
- Fiorio, Jhonatan L.,López, Núria,Rossi, Liane M.
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p. 2973 - 2980
(2017/05/31)
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- Organic Compounds
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Described are spiroalkyl- and -alkenylketones and esters thereof, a method for their production and fragrance compositions comprising them.
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Page/Page column 14
(2010/12/18)
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- Synthesis of spirocyclic butenolides by ring closing metathesis
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Spirocyclic butenolides were efficiently prepared by a ring closing metathesis strategy.
- Albrecht, Uwe,Langer, Peter
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p. 4648 - 4654
(2007/10/03)
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- Synthesis of carbo- and heterocyclic aldehydes bearing an adjacent donor group - Ozonolysis versus OsO4/KIO4-oxidation
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The synthesis of carbo- and heterocyclic aldehydes bearing an ipso-methoxy group is investigated. The synthetic sequence is based on an initial Grignard addition of an olefin to a cyclic ketone followed by methylation of the resulting tertiary alcohol. The terminal olefin serves as precursor for the aldehyde functionality. Oxidation by ozonolysis turned out to depend significantly on the distance of the donor methoxy group. The observed side reactions could be circumvented by applying a one-pot OsO4 mediated diol formation followed by Malaprade oxidation using KIO4. A series of carbo- and heterocyclic precursors were successfully converted to the title products. Springer-Verlag 2004.
- Mihovilovic, Marko D.,Spina, Markus,Mueller, Bernhard,Stanetty, Peter
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p. 899 - 909
(2007/10/03)
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- OXAZOLIDINONE AND / OR ISOXAZOLINE DERIVATIVES AS ANTIBACTERIAL AGENTS
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A compound of the formula (I), or a pharmaceutically-acceptable salt, or in-vivo hydrolysable ester thereof: formula (I) wherein in (I) C is for example formula (D), formula (E), formula (H) wherein A and B are independently selected from (i) formula (J)
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- Cyclopentylalkyl-nitriles
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The present invention provides compounds of formula I wherein R1and R3are independently H or C1-3alkyl, and R2is H, C1-3alkyl, methylene or ethylidene, with the proviso that R1and R2are not simultaneously H; n is 0 or 1; and - - -is a single or a double bond, wherein a maximum of two double bonds are present in the compound. Compounds of formula II are also provided: wherein A is selected from the group of CR4R5OH, CR4R5OC(O)R6, CO2R6, CN and C(O)R4; R1, R3, R4, and R5are independently H or C1-3-alkyl; R2is H, C1-3-alkyl, methylene, or ethylidene; R6is H, C1-3alkyl, C2-4alkenyl, or alkinyl; n is 0 or 1; and - - -is a single or a double bond, wherein a maximum of two double bonds are present. Compositions containing compounds of formulae I and II, as well as methods for imparting fragrance to substrates using such compounds are also provided.
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- Synthesis of spirocyclic butenolides by ring closing metathesis
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Spirocyclic butenolides were efficiently prepared by a ring closing metathesis strategy.
- Langer, Peter,Albrecht, Uwe
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p. 1841 - 1842
(2007/10/03)
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- Indole derivatives as 5-HT1-like agonists for use in migraine
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The present invention relates to 3,5-disubstituted indole compounds which are selective agonists which act on 5-hdroxytryptamine receptors useful in the treatment of migraine.
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- Synthesis and Applications of Tetrahydrofuran-Stable Substituted (3-Lithioxyalkyl)- and (4-Lithioxyalkyl)lithiums, Modified with Magnesium 2-Ethoxyethoxide
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Substituted hydroxyalkyl phenyl sulfides 3 have been synthesized from the corresponding allylic or homoallylic alcohols 2. Regiospecific cleavage of the C - SPh bond of the sulfides 3 by lithium dispersion in tetrahydrofuran (THF) led to the synthesis of substituted (3-lithioxyalkyl)- and (4-lithioxyalkyl)lithiums 4, most of which share the ω carbon with a carbocyclic ring. The organolithiums were modified with magnesium 2-ethoxyethoxide in order to suppress their reactivity toward THF cleavage, thus offering the advantage of preparing storable ethereal solutions of certain types of (lithioxyalkyl)lithiums. This strategy appears to be of rather broad scope. The functionalized organolithiums prepared in this way react normally with electrophilic reagents with yields in the range 35-55%. Thus, carboxylations of 4 yielded lactones 5, some of which are natural products, while reactions of 4 with benzophenone and cyclic ketones yielded 1,4- and 1,5-diols 6 and 7, respectively.
- Kostas, Ioannis D.,Screttas, Constantinos G.
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p. 5575 - 5577
(2007/10/03)
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- Synthesis of spiranic heterocycles by induced decomposition of unsaturated peroxides
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Induced decomposition of unsaturated peroxides in a good hydrogen-donor solvent leads to the functionalization of the latter.If the peroxide contains a cycle on the carbon next to the O-O bond, the reaction gives spirans with an oxiran, an oxetan or a tetrahydrofuran ring in good or even excellent yields.Keywords: unsaturated peroxide / spiranic heterocycles / induced decomposition / homolytic intramolecular substitution / radical addition
- Montaudon, Evelyne,Kappes, Regina,Lemee, Laurent,Campagnole, Monique,Bourgeois, Marie-Josephe
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p. 253 - 261
(2007/10/02)
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- AN EPISULFONIUM ION MEDIATED RING EXPANSION OF 1-ALKENYLCYCLOALKANOLS
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It has been found that TBDMS ethers of 1-alkenylcycloalkanols are readily rearranged to the ring expanded α-(1-phenylthioalkyl)cycloalkanones in high yields via episulfonoium ions.
- Kim, Sunggak,Park, Jung Ho
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p. 6181 - 6184
(2007/10/02)
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- Photooxygenation of 1-Vinylcycloalkenes. The Competition between "Ene" Reaction and Cycloaddition of Singlet Oxygen
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The competition between the "ene" reaction and 1,4-cycloaddition reaction of 1O2 in a series of 1-vinylcycloalkenes (n = 5-10, 12) and 1-isopropenylcycloalkenes (n = 6-8) was studied.Ring size had a profound effect.When n = 5 or 7, products of the "ene" reaction predominated, but as ring size increased cycloaddition competed closely with the "ene" process, the crossover being at ring size 10. 1-Vinylhexenes constituted an exception with 1,4-cycloaddition greatly predominant. "Ene" products were almost exclusively conjugated diene hydroperoxides or secondary products derived from them; small amounts of unconjugated diene hydroperoxides were formed only when n = 9, 10, or 12.The influence of ring size of the "ene" to cycloaddition product ratio is compared with the rates of photooxygenation and the degree of syn-regiospecificity exhibited by (Z)-1-methylcycloalkenes and attributed to the same mainly conformational factors, as is the geometry of the "ene" products.The 1,4-cycloaddition products were converted to furans by means of ferrous sulfate.
- Herz, Werner,Juo, Rouh-Rong
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p. 618 - 627
(2007/10/02)
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- Autoxidation of Vinylcyclopentane, Vinylcyclohexane, and 4-Vinylcyclohex-1-ene
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The title olefins were oxidized with molecular oxygen at 75-80 deg C.About 40percent of the oxygen absorbed were found by iodometric titration as peroxidic oxygen.The reaction products were analyzed by a combination of chemical methods, gas chromatography, and 13C-n.m.r.-spectroscopy.Vinylcyclopentane and vinylcyclohexane are attacked preferably at the tertiary allylic C-H-bonds giving almost equimolar mixtures of the corresponding allylisomeric hydroperoxides.In the case of 4-vinylcyclohex-1-ene the C-H-bonds in position 6 are preferably attacked, but products of attack on the other allylic C-H-bonds also could be identified.In all cases the amount of products which could not be detected gaschromatographically was determined by balance experiments in the presence of an internal standard.
- Biela, R.,Bilas, W.,Ihsan, U.,Pritzkow, W.,Schmidt-Renner, W.
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p. 893 - 900
(2007/10/02)
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- THE DIELS-ALDER REACTION OF METHYL PROPIOLATE WITH 1-VINYLCYCLOALKENES
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The Diels-Alder reaction of methyl propiolate with 1-vinylcycloalkenes was used to assess the influence of ring strain on the regioselectivity of such cycloadditions: the ratio of 1,2,3- to 1,2,4-adducts increased with increasing size of the cycloalkene.
- Markgraf, J. Hodge,Greeno, Edward W.,Miller, Michael D.,Zaks, William J.,Lee, George A.
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p. 241 - 244
(2007/10/02)
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- Manufacture of gamma halogen substituted adducts
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Halogen-substituted olefin addition compounds that contain a carbonyl group are formed by oxidatively adducting an olefin and a carbonyl compound such as a ketone, aldehyde, or ester. The method consists of reacting the olefin and the carbonyl component, in solution, with an oxidizing ion of manganese, cerium or vanadium in the presence of fluoride, chloride or bromide ion. This ionic component is incorporated in the adduct and appears on the olefin-derived carbon atom gamma to the carbonyl group. The gamma halogen substituted adducts are readily converted to cyclopropane derivatives, including pyrethroid intermediate compounds.
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