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Alkenyl
Terms modified by Alkenyl Selected AbstractsFormation of (,-Alkenyl)- and (,-Vinylidene)palladium and -platinum Complexes by Oxidative Addition of 4,4-Dichloro-1,1-diphenyl-2-azabuta-1,3-diene , The Molecular Structure of an Unusual Asymmetric (,-Vinylidene)Pd,Pd ComplexEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 3 2003Michael Knorr Abstract 4,4-Dichloro-1,1-diphenyl-2-azabuta-1,3-diene (1) oxidatively adds to [Pd(PPh3)4] and [Pt(C2H4)(PPh3)2] giving rise to the ,-alkenyl complexes trans -[MCl{[C(Cl)=C(H),N=CPh2]}(PPh3)2] (2a: M = Pd; 2b: M = Pt). When 1 is treated with [Pd(PPh3)4] in a 1:2 ratio in refluxing toluene, the dimetallic ,-vinylidene complex [(PPh3)ClPd{,-[C=C(H),N=CPh2]}PdCl(PPh3)2] (3) is formed. In this fluxional compound, a PPh3 ligands migrates in a reversible manner between the two Pd centers. Substitution of the PPh3 ligands of 3 by 2 equiv. of Ph2PCH2PPh2 affords the A-frame complex [ClPd(,-dppm)2{,-[C=C(H),N=CPh2]}PdCl] (4). (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Enantioselective Addition of Boronates to Chromene Acetals Catalyzed by a Chiral Brønsted Acid/Lewis Acid System,ANGEWANDTE CHEMIE, Issue 39 2010Philip N. Moquist Chirale ,,,-Dihydroxycarbonsäuren katalysieren die enantioselektive Addition von Alkenyl- und Arylboronaten an Chromenacetale. Die beste Carbonsäure ist das gezeigte, leicht zugängliche Tartarsäureamid. Zugabe von Lanthanoidtriflaten beschleunigt die Reaktion. Spektroskopische und kinetische Studien offenbaren einen Austauschprozess, der zu einem reaktiven Dioxoborolan-Intermediat führt, das eine enantioselektive Addition an das aus dem Chromenacetal gebildeten Pyrylium-Ion eingeht. [source] Palladium-Catalyzed Coupling Reactions of Thioimidate N-Oxides: Access to ,-Alkenyl- and ,-Aryl-Functionalized Cyclic Nitrones,ANGEWANDTE CHEMIE, Issue 3 2010Julie Schleiss Überraschend hilfreich waren chirale Thioimidat-N-oxide bei der Synthese aryl- und vinylsubstituierter cyclischer Ketonitrone durch eine Liebeskind-Srogl-Reaktion. Dieser neue Ansatz scheint effizient und breit anwendbar zu sein (siehe Schema). [source] Highly Selective Oxidation of Organosilanes to Silanols with Hydrogen Peroxide Catalyzed by a Lacunary Polyoxotungstate,ANGEWANDTE CHEMIE, Issue 47 2009Ryo Ishimoto Silanolsynthese: Das lakunare Polyoxowolframat (nBu4N+)4[,-SiW10O34(H2O)2] (I) mit zwei Leerstellen ist ein effizienter Homogenkatalysator für die hoch selektive Oxidation von Organosilanen zu Silanolen mit 30,60,% H2O2. Silane 1 mit Aryl-, Alkyl-, Alkenyl-, Alkinyl- und Alkoxygruppen werden in hohen Ausbeuten chemoselektiv zu den jeweiligen Silanolen 2 umgesetzt, wobei nur ein Äquivalent an wässrigem H2O2 in Bezug auf das Substrat benötigt wird. [source] Structure-Guided Directed Evolution of Alkenyl and Arylmalonate DecarboxylasesANGEWANDTE CHEMIE, Issue 41 2009Krzysztof Okrasa Dr. Gewusst wie: Die Röntgenkristallstruktur einer Arylmalonat-Decarboxylase (AMDase) im Komplex mit einem mechanismusbasierten Inhibitor, der in das Dioxyanion-Loch des aktiven Zentrums bindet, bietet Einblicke in die Wirkungsweise dieses Enzyms. Die Struktur diente als Ausgangspunkt für die Erweiterung des biokatalytischen Repertoires der AMDase auf eine Bandbreite von ,-Alkenyl- und ,-Arylmalonat-Substraten. [source] Trends in Organocatalytic Conjugate Addition to Enones: An Efficient Approach to Optically Active Alkynyl, Alkenyl, and Ketone Products,ANGEWANDTE CHEMIE, Issue 40 2009Márcio, Weber Paixão Dr. Drei in einem: Eine organokatalytische Tandemstrategie erwies sich als schnelles und effizientes Verfahren für den Aufbau einer Bibliothek aus optisch aktiven Alkinyl-, Alkenyl- und Keto-Derivaten ausgehend von cyclischen Enonen und ,-Ketosulfonen (siehe Schema; R=Aryl, R,=H oder Alkyl). [source] ChemInform Abstract: Nickel-Catalyzed Efficient and Practical Suzuki,Miyaura Coupling of Alkenyl and Aryl Carbamates with Aryl Boroxines.CHEMINFORM, Issue 27 2010Li Xu Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Palladium-Catalyzed Direct Arylation-Based Domino Synthesis of Annulated N-Heterocycles Using Alkenyl or (Hetero)Aryl 1,2-Dihalides.CHEMINFORM, Issue 9 2010Lutz Ackermann Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Trends in Organocatalytic Conjugate Addition to Enones: An Efficient Approach to Optically Active Alkynyl, Alkenyl, and Ketone Products.CHEMINFORM, Issue 3 2010Marcio Weber Paixao Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Transition-Metal-Free Oxidative Homocoupling of Aryl, Alkenyl, and Alkynyl Grignard Reagents with TEMPO.CHEMINFORM, Issue 50 2009Modhu Sudan Maji Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: A One-Pot, Stereoselective Synthesis of 2-Ethoxycarbonyl-Substituted 1,3-Dienes and 1,3-Enynes by Hydrostannylation , Stille Tandem Reaction of Tributyltin Hydride with Alkynyl Esters and Alkenyl or Alkynyl Halides.CHEMINFORM, Issue 41 2009Mingzhong Cai Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: One-Pot Hydrosilylation,RCM,Protodesilylation: Application to the Synthesis of ,-Alkenyl ,,,-Unsaturated Lactones.CHEMINFORM, Issue 29 2009Cyril Bressy Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Convenient Synthesis of Alkenyl-, Alkynyl-, and Allenyl-Substituted Imidazo[1,2-a]pyridines via Palladium-Catalyzed Cross-Coupling Reactions.CHEMINFORM, Issue 19 2008Cecile Enguehard-Gueiffier Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Novel Formation of 2-Arylquinolines and 1,3-Benzoxazines from 2-(1-Alkenyl)acylanilides and Active Halogens.CHEMINFORM, Issue 4 2008Kentaro Okuma Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Stereospecific Cross-Coupling of ,-(Thiocarbamoyl)organostannanes with Alkenyl, Aryl, and Heteroaryl Iodides.CHEMINFORM, Issue 20 2007J. R. Falck Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Palladium-Catalyzed Phosphorus,Carbon Bond Formation: Cross-Coupling Reactions of Alkyl Phosphinates with Aryl, Heteroaryl, Alkenyl, Benzylic, and Allylic Halides and Triflates.CHEMINFORM, Issue 42 2005Karla Bravo-Altamirano Abstract For Abstract see ChemInform Abstract in Full Text. [source] Alkenyl- and Aryl[2-(hydroxymethyl)phenyl]dimethylsilanes: An Entry to Tetraorganosilicon Reagents for the Silicon-Based Cross-Coupling Reaction.CHEMINFORM, Issue 39 2005Yoshiaki Nakao Abstract For Abstract see ChemInform Abstract in Full Text. [source] Palladium-Catalyzed Oxidative Alkoxylation of ,-Alkenyl ,-Diketones to Form Functionalized Furans.CHEMINFORM, Issue 28 2004Xiaoqing Han Abstract For Abstract see ChemInform Abstract in Full Text. [source] A Straightforward Synthesis of (E)-,-Alkenyl-,,,-Unsaturated ,-Lactones by a Tandem Ring-Closing/Cross-Coupling Metathesis Process.CHEMINFORM, Issue 5 2004Marie-Alice Virolleaud Abstract For Abstract see ChemInform Abstract in Full Text. [source] Homocoupling of Alkyl-, Alkenyl-, and Arylboronic Acids.CHEMINFORM, Issue 4 2003J. R. Falck Abstract For Abstract see ChemInform Abstract in Full Text. [source] ChemInform Abstract: Intramolecular Conjugate Addition of Alkenyl and Aryl Functions to Enones Initiated by Lithium,Iodine Exchange.CHEMINFORM, Issue 12 2002Edward Piers Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Stereoselective Synthesis of (Z)-Enethiols and Their Derivatives: Vinylic SN2 Reaction of (E)-Alkenyl(phenyl)-,3 -iodanes with Thioamides.CHEMINFORM, Issue 51 2001Masahito Ochiai' Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Diastereo- and Enantioselective Intramolecular [2+2],Photocycloaddition Reactions of 3-(,,-Alkenyl)- and 3-(,,-Alkenyloxy)-Substituted 5,6-Dihydro-1H -pyridin-2-onesCHEMISTRY - A EUROPEAN JOURNAL, Issue 14 2010Dominik Albrecht Dr. Abstract 3-(,,-Alkenyl)-substituted 5,6-dihydro-1H -pyridin-2-ones 2,4 were prepared as photocycloaddition precursors either by cross-coupling from 3-iodo-5,6-dihydro-1H -pyridin-2-one (8) or,more favorably,from the corresponding ,-(,,-alkenyl)-substituted ,-valerolactams 9,11 by a selenylation/elimination sequence (56,62,% overall yield). 3-(,,-Alkenyloxy)-substituted 5,6-dihydro-1H -pyridin-2-ones 5 and 6 were accessible in 43 and 37,% overall yield from 3-diazopiperidin-2-one (15) by an ,,,-chloroselenylation reaction at the 3-position followed by nucleophilic displacement of a chloride ion with an ,-alkenolate and oxidative elimination of selenoxide. Upon irradiation at ,=254,nm, the precursor compounds underwent a clean intramolecular [2+2] photocycloaddition reaction. Substrates 2 and 5, tethered by a two-atom chain, exclusively delivered the respective crossed products 19 and 20, and substrates 3, 5, and 6, tethered by longer chains, gave the straight products 21,23. The completely regio- and diastereoselective photocycloaddition reactions proceeded in 63,83,% yield. Irradiation in the presence of the chiral templates (,)- 1 and (+)- 31 at ,75,°C in toluene rendered the reactions enantioselective with selectivities varying between 40 and 85,%,ee. Truncated template rac - 31 was prepared as a noranalogue of the well-established template 1 in eight steps and 56,% yield from the Kemp triacid (24). Subsequent resolution delivered the enantiomerically pure templates (,)- 31 and (+)- 31. The outcome of the reactions is compared to the results achieved with 4-substituted 5,6-dihydro-1H -pyridin-2-ones and quinolones. [source] Diastereoselective Synthesis of Five- and Seven-Membered Rings by [2+2+1], [3+2], [3+2+2], and [4+3] Carbocyclization Reactions of ,-Substituted (Alkenyl)(methoxy)carbene Complexes with Methyl Ketone Lithium EnolatesCHEMISTRY - A EUROPEAN JOURNAL, Issue 17 2005José Barluenga Prof. Dr. Abstract ,-Substituted alkenylcarbene complexes react with methyl ketone lithium enolates to give different carbocyclization products depending on the structure of the lithium enolate, on the metal of the carbene complex, and on the reaction media. Thus, the reactions of aryl and alkyl methyl ketone lithium enolates with ,-substituted alkenyl chromium and tungsten carbene complexes in diethyl ether afford 1,3-cyclopentanediol derivatives derived from a formal [2+2+1] carbocyclization reaction. However, the lithium enolates of acetone and tungsten complexes furnish formal [3+2+2] carbocyclization products. In the case of alkynyl methyl ketone lithium enolates, competitive formal [2+2+1] and [3+2] carbocyclization reactions occur and 1,3-cyclopentanediol and 3-cyclopentenol derivatives are formed. Conversely, alkenyl methyl ketone lithium enolates react with alkenylcarbene complexes under the same reaction conditions to form 2-cycloheptenone derivatives by a formal [4+3] carbocyclization reaction. Finally, when the reaction was performed in the presence of a coordinating medium, the [3+2] carbocyclization pattern was observed independently of the nature of the methyl ketone lithium enolate used. Los complejos alquenilcarbeno , -sustituidos reaccionan con enolatos de litio de metil cetonas para dar diferentes productos de carbociclación dependiendo de la estructura del enolato de litio, del metal del complejo carbeno y del medio de reacción. Así, la reacción de enolatos de litio de aril y alquil metil cetonas con complejos alquenilcarbeno de cromo y wolframio , -sustituidos en dietil eter origina derivados de 1,3-ciclopentanodiol, derivados de una reacción de carbociclación formal [2+2+1]. Sin embargo, el enolato de litio de la acetona y complejos de wolframio dan lugar a productos de carbociclación formal [3+2+2]. En el caso de enolatos de litio de alquinil metil cetonas, se observa la formación de una mezcla de derivados de 1,3-ciclopentanodiol y 3-ciclopentenol derivados de reacciones de carbociclación formal [2+2+1] y [3+2] competitivas. Por el contrario, los enolatos de litio de alquenil metil cetonas reaccionan con complejos alquenilcarbeno en las mismas condiciones de reacción para generar derivados de 2-cicloheptenona a través de una reacción de carbociclación formal [4+3] Finalmente, cuando la reacción se lleva a cabo en presencia de PMDTA, un medio coordinante, se observa el modelo de carbociclación formal [3+2], independientemente de la naturaleza del enolato de litio utilizado. [source] Indium Triiodide Catalyzed Direct Hydroallylation of EstersEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 18 2010Yoshihiro Nishimoto Abstract The InI3 -catalyzed hydroallylation of esters by using hydro- and allysilanes under mild conditions has been accomplished. Many significant groups such as alkenyl, alkynyl, cyano, and nitro ones survive under these conditions. This reaction system provided routes to both homoallylic alcohols and ethers, in which either elimination of the alkoxy moiety or of the carbonyl oxygen atom could be freely selected by changing the substituents on the alkoxy moiety and on the hydrosilane. In addition, the hydroallylation of lactones took place without ring cleavage to produce the desired cyclic ethers in high yields. [source] Synthesis of Cyclopropanes via Organoiron Methodology: Stereoselective Preparation of Bi(cyclopropyl)sEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 23 2007Rajesh K. Pandey Abstract Cyclopropanation of [2-(alkenyl)pentenediyl]Fe(CO)3 complexes (4) proceeds in a diastereoselective fashion to afford [2-(cyclopropyl)pentenediyl]Fe(CO)3. The relative stereochemistry of the products was established by X-ray crystallography. The diastereoselectivity is rationalized on approach of the cyclopropanation reagent on the sterically more exposed face of 4. Oxidatively induced reductive elimination afforded stereodefined bi(cyclopropyl)s. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Synthesis of Functionalized 1-Substituted Alkenylsilanols and Establishment of Conditions for Their Palladium-Catalyzed Cross-Coupling Reactions To Afford 1-Substituted Styrene DerivativesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 20 2004Sunil K. Ghosh Abstract An efficient method for the quantitative conversion of 1-substituted alkenyl(phenyl)silanes into the corresponding alkenylsilanols has been developed and used in their palladium(0)-catalyzed, tetrabutylammonium fluoride-promoted cross-coupling reaction with aryl iodides. Copper(I) chloride modulated the reactivity of TBAF in such a way that it virtually eliminated the protiodesilylation of alkenylsilanols, thus favoring the formation of ipso -coupled products. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] Nine Times Fluoride can be Good for your Syntheses.ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 17 2009Not just Cheaper: Nonafluorobutanesulfonates as Intermediates for Transition Metal-Catalyzed Reactions Abstract How much fluoride is good for a strong electron-withdrawing effect? In this review we summarize recent results on the use of perfluoroalkanesulfonates, in particular of the cost effective nonafluorobutanesulfonates (nonaflates), in transition metal-catalyzed reactions and a few other typical transformations. During the last decade many advantages over the commonly used triflates have been discovered. The generation of alkenyl and (het)aryl nonaflates and their applications in metal-catalyzed processes such as Heck, Suzuki, Sonogashira, Stille, and Negishi couplings or amination reactions are described. Although far from a systematic investigation, all the presented results clearly demonstrate the many advantages of nonaflates and of similar higher fluorinated sulfonates in laboratory and industrial scale organic synthesis. [source] The no-carrier-added synthesis of bromine-76 labeled alkenyl and alkynyl bromides using organotrifluoroboratesJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 1 2006George W. Kabalka Abstract A straightforward radiobromination procedure has been developed for the construction of radiobrominated alkenyl and alkynyl bromides. The organotrifluoroborates used as the reactive intermediates are unique in that they are quite polar and thus readily separated from the desired products. Copyright © 2005 John Wiley & Sons, Ltd. [source] Incorporation of a new alkenyl-based nonionic surfmer into acrylic latexesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 17 2004Esteban Aramendia Abstract The mechanisms by which a new nonionic alkenyl-based surfmer (Maxemul 5011Ô) was involved in acrylic emulsion polymerization were investigated. No proof of homopolymerization or of chain transfer to surfmer was obtained under the conditions studied. The effect of the initiator type, feeding time of the surfmer, particle size of the seed, and surfmer concentration, on kinetics and surfmer incorporation showed that the surfmer reacted mainly by copolymerization with the monomers in the outer shell of the polymer particles. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4202,4211, 2004 [source] | |||||||||||||||||||||||||