- 2-Vinyl-1,1,2-trihalocyclopropanes - Valuable five carbon cyclopropane and cyclopropene synthetic intermediates
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The dichloro- and dibromocarbene adducts of chloroprene and 2,3-dichlorobutadiene are readily dehalogenated by reaction with methyllithium to give 1-halo-2-vinylcyclopropenes which on further lithium-halogen exchange give synthetically useful 1-lithio-2-vinylcyclopropenes. Trapping of 1-lithio-2-(1-chlorovinyl)cyclopropene with methyl chloroformate leads to a very unusual cyclononadienyne.
- Al Dulayymi, Ahmad R.,Baird, Mark S.
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- Efficient and stereoselective nitration of mono- and disubstituted olefins with AgNO2 and TEMPO
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Nitroolefin is a common and versatile reagent. Its synthesis from olefin is generally limited by the formation of mixture of cis and trans compounds. Here we report that silver nitrite (AgNO2) along with TEMPO can promote the regio- and stereoselective nitration of a broad range of olefins. This work discloses a new and efficient approach wherein starting from olefin, nitroalkane radical formation and subsequent transformations lead to the desired nitroolefin in a stereoselective manner.
- Maity, Soham,Manna, Srimanta,Rana, Sujoy,Naveen, Togati,Mallick, Arijit,Maiti, Debabrata
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supporting information
p. 3355 - 3358
(2013/04/10)
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- Living anionic polymerization of 1,4-divinylbenzene and its isomers
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The anionic polymerization of 1,4-divinylbenzene (1) and its ortho (2) and meta isomers (3) were studied under a variety of conditions. One of the two vinyl groups of 1 was selectively and exclusively polymerized in a living manner by the addition of a suitable additive under the conditions of -78 C for 1 min and -95 C for 30 min. Under such conditions, the unwanted addition reaction of the chain-end anion to the pendant vinyl group was almost suppressed and soluble polymers with predictable molecular weights of up to 60 500 g/mol and narrow molecular weight distributions (Mw/Mn 1.05) were quantitatively obtained. The amount of dimerized chain produced by the addition reaction was negligible or very small (5%). The effective additives in the polymerization involve potassium alkoxides and phenoxides, derived from tert-butyl alcohol, sec-butyl alcohol, 2,4-dimethyl-3-pentanol, 1-methylcyclohexanol, 1:2,5:6-di-O-isopropylidene-α-d-glucofuranose, phenol, 1-naphthol, and 2,6-di(tert-butyl)-4-methylphenol, and potassium carboxylate derived from pivalic acid. The living polymer of 1 was not stable at -78 C after 5 min or longer times, but very stable at -95 C even for 30 min. The chain-end anion could be stabilized by end-capping with tert-butyl methacrylate and 1,1-diphenylethylene, and the resulting anions remained unchanged at -78 C even after several hours.
- Tanaka, Shunsuke,Matsumoto, Masayoshi,Goseki, Raita,Ishizone, Takashi,Hirao, Akira
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p. 146 - 154
(2013/03/14)
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- Molecular Fingerprints With Enhanced Identifying Capability, Method for Preparing Same and Use Thereof
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The invention concerns a method for preparing a molecular fingerprint comprising sites for identifying at least one target molecule, said fingerprint being obtained from at least one master molecule of polymeric type, called master polymer. The invention is characterized in that said master polymer is different from the target molecule(s), and is capable of being eliminated by degradation and/or washing, and that at least 5% in number of monomer units constituting the master polymer are involved in the formation of the sites for identifying the target molecule(s).
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- Intramolecular heck reactions of unactivated alkyl halides
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A method has been developed for achieving palladium-catalyzed intramolecular Heck reactions of unactivated, β-hydrogen-containing alkyl bromides and chlorides. The data from a stereochemical investigation are consistent with carbon-carbon bond formation via an alkylpalladium, rather than a radical, intermediate. Copyright
- Firmansjah, Luke,Fu, Gregory C.
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p. 11340 - 11341
(2008/03/30)
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- Phosphepines: Convenient access to phosphinidene complexes
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Reaction of o-diethynylbenzene with transition metal-complexed primary phosphines gives in a single base-induced step stable phosphepine complexes as confirmed by X-ray data. At 75-80 °C these phosphepines undergo clean cheletropic elimination of naphthalene to give transient carbene-like phosphinidene complexes that can be trapped in high yield by alkenes, alkynes, and alcohols. Copyright
- Borst, Mark L. G.,Bulo, Rosa E.,Winkel, Christiaan W.,Gibney, Daniele J.,Ehlers, Andreas W.,Schakel, Marius,Lutz, Martin,Spek, Anthony L.,Lammertsma, Koop
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p. 5800 - 5801
(2007/10/03)
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- Pd-Catalyzed Cross-Coupling of Haloarenes and Chloroarene-Cr(CO) 3 Complexes with Stabilized Vinyl- and Allylaluminium Reagents
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The palladium-catalyzed cross-coupling of intramolecularly stabilized divinyl- and diallylaluminium compounds 1 and 2 with haloarenes and chloroarene-Cr(CO)3 complexes has been studied. The coupling products were obtained in high yields (up to
- Schumann, Herbert,Kaufmann, Jens,Schmalz, Hans-Günther,B?ttcher, Andreas,Gotov, Battsengel
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p. 1783 - 1788
(2007/10/03)
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- Dosing form for reagents, use of said dosing form in organic chemical synthesis and production of said dosing form
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A dosing form for at least one solid reagent for use in conventional organic and inorganic synthesis, in parallel synthesis, and in split and mix synthesis in combinatorial chemistry is provided as compressed tablets each containing the same predetermined amount of said at least one reagent embedded in a polymer matrix comprising beads of a polymer insoluble in the solvents for the intended synthesis, which tablets are capable of disintegrating in said solvent for release of the at least one reagent and disperse the matrix as polymer beads into the solvent. The polymer beads forming the matrix and the reagents of the dosing form can easily be removed by filtration in order to separate these from a formed soluble product. In a method for producing the dosing form, beads of one or more polymers are mixed with the reagents and compressed into tablets after pre-treatment with an aprotic organic solvent.
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- Synthesis of o-Dialkenylbenzenes and Indenes Using Heck and Oxypalladation Reactions
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o-Bromostyrenes 2-Br react with various alkenes in the presence of palladium catalysts to give either substituted indene 6 or o-diethenylbenzene derivatives 3, depending on the reaction conditions.Under oxidative conditions the latter can be cyclized to indene derivatives as well. - Keywords: Cross-coupling, Heck; Palladium catalysis; Indanes; Arenes, dialkenyl-N
- Braese, Stefan,Ruemper, Joerg,Voigt, Katharia,Albecq, Stephane,Thurau, Gert,et al.
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p. 671 - 678
(2007/10/03)
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- New heck-type coupling reactions of natural tetrapyrroles - Synthesis of porphyrinoligomers bridged by divinyl- and trivinylbenzene
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Using palladium(0)-catalyzed coupling reactions we were able to synthesize mono-, di-, and trimeric porphyrins linked by di- and trivinylbenzenes. The reactions were carried out with palladium(II) acetate in DMF under phase-transfer conditions. These coupling conditions are new in the field of porphyrin chemistry and proved to be a useful tool in the synthesis of C-C linked oligomeric porphyrins, as these compounds can be obtained in a simple one pot reaction with good yields.
- Gauler, Rainer,Risch, Nikolaus
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p. 1193 - 1200
(2007/10/03)
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- Fluorescent compounds
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Novel compounds obtainable by reacting together an imido-reagent such as diphenylphosphonimido-triphenylphosphorane), or a phosphine oxide such as p-tolyldiphenylphosphine oxide, with a chelate of a transition or lanthanide or actinide metal, such as tris(dibenzoylmethide)europium III, have the property of fluorescing in UV radiation. The invention includes solid polymer bodies containing such compounds, or chelates of transition or lanthanide or actinide metals generally, the bodies having the property of emitting light or infra-red radiation when subjected to a flux of ultra-violet or ionising radiation by virtue of internally generated, e.g. by tritium ionising radiation. The body is preferably of polystyrene formed by polymerising the monomer in the presence of the compound or metal chelate.
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- Fluorescent compounds
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Novel compounds obtainable by reacting together an imido-reagent such as diphenylphosphonimidotriphenylphosphorane), or a phosphine oxide such as p-tolyldiphenylphosphine oxide, with a chelate of a transition or lanthanide or actinide metal, such as tris(dibenzoylmethide) europium III, have the property of fluorescing in UV radiation. The invention includes solid polymer bodies containing such compounds, or chelates of transition or lanthanide or actinide metals generally, the bodies having the property of emitting light or infra-red radiation when subjected to a flux of ultra-violet or ionising radiation by virtue of internally generated, e.g. by tritium ionising radiation. The body is preferably of polystyrene formed by polymerising the monomer in the presence of the compound or metal chelate.
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- Radical-Stabilization-Energy - the MMEVBH Force Field
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Making use of the VB method of Malrieu et al. a force field has been developed, which allows to calculate heats of formation of hydrocarbons (conjugated and non-conjugated olefins, radicals and diradicals) with high accuracy.With this method radical stabilization energies (RSE) for a great number of delocalized radicals are calculated and compared with experimental values, derived from shock-tube measurements of dissociation energies or from rotational barriers of substituted olefins.A detailed analysis of the RSE with respect to structure, substituents, strain, and aromaticity is presented. - Key Words: Resonance energy / Heats of formation / Single pulse shock tube / Intrisic rotational barrier
- Roth, Wolfgang R.,Staemmler, Volker,Neumann, Martin,Schmuck, Carsten
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p. 1061 - 1118
(2007/10/02)
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- Process for preparing vinylically-unsaturated compounds (II)
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A process for preparing a vinylically-unsaturated product compound comprises reacting a halogenated organic compound with a hydrolytically-stable, vinylically-unsaturated precursor compound in the presence of (a) a homogeneous zerovalent palladium catalyst complex, (b) an inorganic hydrogen halide acceptor and (c) diluent, wherein the diluent is water or an aqueous solution containing up to 95% by volume of an organic solvent. The halogenated organic compound is selected from aryl halides, benzyl halides or vinylic halides. The hydrolytically-stable, vinylically-unsaturated precursor compound is selected from hydrocarbon compounds or compounds containing at least one of an oxygen atom, a nitrogen atom, a sulfur atom, a phosphorus atom, silicon atom or a combination thereof.
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- On the Cyclization of all-cis-1,10-Dibromo-2,5,8-decatriene with Magnesium
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On reaction with magnesium in THF at -70 deg C, the title compound 6 yields about equal amounts of 7-vinyl-1,4-cyclooctadiene (11), all-cis-1,4,7-cyclodecatrien 12), 4,5-divinyl-1-cyclohexene (13), as well as 1,2-divinylbenzene (14) in addition to polymeric material.
- Brudermueller, Martin,Musso, Hans
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p. 2255 - 2256
(2007/10/02)
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- USES OF ADSORBED REAGENTS IN THE SYNTHESIS OF REACTIVE MOLECULES VIA ELIMINATION REACTIONS
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The synthesis of reactive molecules (in vacuo) using reagents adsorbed on inert surfaces to effect elimination reactions has been investigated.Potassium t-butoxide adsorbed on Chromosorb W can be used to generate methylenecyclopropene from 2-chloromethylenecyclopropane and 1-vinylcyclopropene from either 1,4-dichlorospiropentane or 1-chloro-2-vinylcyclopropane.Both compounds can be characterized at low temperature using NMR and IR spectroscopy.Methyllithium on glass helices has been used in the reductive elimination of halogen from vicinal cyclopropyl dihalides to yield cyclopropenes. β-Halocyclopropylsilanes can be converted in high yield to the corresponding cyclopropene using tetra-n-buthylammonium fluoride deposited on glass helices.The fluoride route has been used to generate bicyclohept-(1,6)-ene and bicyclohept-(1,7)-ene in the gas phase under conditions wich allow either spectroscopic characterization or trapping as Diels-Alder adducts.
- Billups, W. E.,Lin, Long-Jin
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p. 1575 - 1580
(2007/10/02)
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- Thermochemistry of Phenyl-Substituted Benzobicyclohex-2-enes
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The thermal rearrangements of benzobicyclohex-2-ene (21) and its phenyl-substituted analogues 22-25 (Scheme V) as models of sterically constrained phenylcyclopropanes have been studied by means of flash vacuum pyrolysis.In most cases the major pathway was cleavage of the "internal" C(1)-C(5) cyclopropane bond followed by a 1,2-hydrogen or a 1,2-phenylshift in the resulting biradical.For 6-phenylbenzobicyclohex-2-ene (25), substantial cleavage of the "external" C(1)-C(6) cyclopropane bond was observed, the phenyl substitution pattern being favorable for stabilization of the resulting biradical 62.Phenyl-substituted 1,2-dihydronaphthalenes 44, 47, 51, and 55 are among the major products.Comparison of the plots of the pyrolysis product composition of the 1,2-dihydronaphthalenes vs. pyrolysis temperature with similar plots of the title compounds (22-25) suggested that some of the minor products, viz., the 1,2-divinylbenzenes 31, 42, and 49, are formed via carbenes 30, 41, 50, 57, and 61 rather than via biradicals.Especially at higher pyrolysis temperatures, a large amount of an oxidation product, viz., 1- or 2-phenylnaphthalene (48 or 54), is formed.
- Lamberts, Joseph J.,Laarhoven, Wim H.
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p. 100 - 106
(2007/10/02)
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- Vinylbenzyl ester of an N-BOC amino acid
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There is described herein the preparation of vinylbenzyl esters of N-BOC amino acids which upon polymerization with styrene and divinylbenzene provide insoluble polymers useful as starting materials for the solid phase synthesis of peptides.
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