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Electron-Deficient Alkenes (electron-deficient + alkene)
Selected AbstractsChemInform Abstract: Palladium-Catalyzed Direct Cross-Coupling Reaction Between Indenes and Electron-Deficient Alkenes.CHEMINFORM, Issue 43 2010Yun-He Xu Abstract The simple procedure affords the desired dienes in moderate to low yields. [source] ChemInform Abstract: A Facile Generation of C,S Bonds via One-Pot, Odorless and Efficient Thia-Michael Addition Reactions Using Alkyl, Aryl or Allyl Halides, Thiourea and Electron-Deficient Alkenes in Wet Polyethylene Glycol (PEG 200) under Mild Reaction Conditions.CHEMINFORM, Issue 44 2009Habib Firouzabadi 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: Mesoionic Carbenes: Reactions of 1,3-Diphenyltetrazol-5-ylidene with Electron-Deficient Alkenes and Synthesis and Catalytic Activities of the (Tetrazol-5-ylidene)rhodium(I) Complexes.CHEMINFORM, Issue 36 2009Shuki Araki 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: C1 -Symmetrical Ti(OTos)2 - and TiCl2 -TADDOLate-Catalyzed 1,3-Dipolar Cycloaddition Reactions of Nitrones to Electron-Deficient Alkenes.CHEMINFORM, Issue 38 2008Yan-xia Wang 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: Indium(III) Acetate-Catalyzed Intermolecular Radical Addition of Organic Iodides to Electron-Deficient Alkenes.CHEMINFORM, Issue 23 2008Katsukiyo Miura 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] Ionic Liquid, 1-n-Butyl-3-methylimidazolium Bis(trifluoromethanesulfonyl)imide, Resulted in the First Catalyst-Free Aminohalogenation of Electron-Deficient Alkenes.CHEMINFORM, Issue 22 2007Yi-Ning Wang 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] Perchloric Acid Impregnated on Silica Gel (HClO4/SiO2): A Versatile Catalyst for Michael Addition of Thiols to the Electron-Deficient Alkenes.CHEMINFORM, Issue 33 2006Abu T. Khan 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] Reaction of an Ammonium Eneselenolate Derived from a Selenothioacetic Acid S-Ester with Electron-Deficient Alkenes and Alkynes.CHEMINFORM, Issue 32 2004Toshiaki Murai Abstract For Abstract see ChemInform Abstract in Full Text. [source] Selective Domino Ring-Closing Metathesis,Cross-Metathesis Reactions Between Enynes and Electron-Deficient Alkenes.CHEMINFORM, Issue 38 2003Frederique Royer Abstract For Abstract see ChemInform Abstract in Full Text. [source] ChemInform Abstract: Thermal- and Microwave-Assisted Hydrogenation of Electron-Deficient Alkenes Using a Polymer-Supported Hydrogen Donor.CHEMINFORM, Issue 49 2001Bimbisar Desai 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] Weak Attractive Interactions between Methylthio Groups and Electron-Deficient Alkenes in peri -Naphthalenes: A Competition with Conjugative EffectsCHEMISTRY - A EUROPEAN JOURNAL, Issue 29 2006Jane O'Leary Dr. Abstract The solid-state conformations of five peri -disubstituted naphthalenes bearing a methylthio group and an electron-deficient alkene indicate a weak attractive interaction between the functional groups in four cases in which out-of-plane displacements lead to a common orientation of the MeS,,,sp2 -C vector to the alkene bond. In some cases the interaction is not strong enough to outweigh the tendency of the alkene to conjugate with the aromatic ring, and in one case this optimisation of conjugation alone controls the molecular conformation. The methylthio group lies close to the aromatic plane in all but one example for which the plane of the sulfide group is presented to the alkene. [source] C-Glycosidations of a 2-Ketohexosyl Bromide with Electrophilic, Radical, and Nucleophilic Anomeric CarbonsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 16 2003Frieder W. Lichtenthaler Abstract The susceptibility of acylated 2-ketohexosyl halides to C-homologation is demonstrated with the easily accessible tri- O -benzoyl-,- D - arabino -hexos-ulosyl bromide 1 as the model compound. C-Glycosidation with an electrophilic anomeric carbon requires prior carbonyl protection, to avoid carbonyl addition by the C-nucleophile, for example, as the cyanohydrin. Silver triflate-promoted reaction with the silylenol ether of acetophenone then efficiently yields the ,-phenacyl product. With thermal (AIBN) or photochemical induction, 1 smoothly generates an anomeric radical , comparatively electrophilic, due to its capto-dative substitution , which exclusively traps hydrogen in the presence of tributyltin and electron-deficient alkenes. With allyltributylstannanes, however, it reacts with high stereoselectivity to afford ,- C -allyl glycosiduloses. The ,-bromoketone functionality in ulosyl bromide 1 is susceptible to Reformatsky conditions: treatment with zinc-copper couple readily generates the 1,2-enolate, a most simple anomeric nucleophile, which effectively adds to aldehydes to give ,- C -hydroxyalkyl glycosiduloses or ,- C -disaccharides (with sugar aldehydes) with a high degree of double stereoselection. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Bifunctional Heterogeneous Catalysis of Silica,Alumina-Supported Tertiary Amines with Controlled Acid,Base Interactions for Efficient 1,4-Addition ReactionsCHEMISTRY - A EUROPEAN JOURNAL, Issue 41 2009Ken Motokura Dr. Abstract We report the first tunable bifunctional surface of silica,alumina-supported tertiary amines (SA,NEt2) active for catalytic 1,4-addition reactions of nitroalkanes and thiols to electron-deficient alkenes. The 1,4-addition reaction of nitroalkanes to electron-deficient alkenes is one of the most useful carbon,carbon bond-forming reactions and applicable toward a wide range of organic syntheses. The reaction between nitroethane and methyl vinyl ketone scarcely proceeded with either SA or homogeneous amines, and a mixture of SA and amines showed very low catalytic activity. In addition, undesirable side reactions occurred in the case of a strong base like sodium ethoxide employed as a catalytic reagent. Only the present SA-supported amine (SA,NEt2) catalyst enabled selective formation of a double-alkylated product without promotions of side reactions such as an intramolecular cyclization reaction. The heterogeneous SA,NEt2 catalyst was easily recovered from the reaction mixture by simple filtration and reusable with retention of its catalytic activity and selectivity. Furthermore, the SA,NEt2 catalyst system was applicable to the addition reaction of other nitroalkanes and thiols to various electron-deficient alkenes. The solid-state magic-angle spinning (MAS) NMR spectroscopic analyses, including variable-contact-time 13C cross-polarization (CP)/MAS NMR spectroscopy, revealed that acid,base interactions between surface acid sites and immobilized amines can be controlled by pretreatment of SA at different temperatures. The catalytic activities for these addition reactions were strongly affected by the surface acid,base interactions. [source] Understanding Sulfone Behavior in Palladium-Catalyzed Domino Reactions with Aryl IodidesCHEMISTRY - A EUROPEAN JOURNAL, Issue 17 2006Inés Alonso Dr. Abstract Unlike traditionally used acyclic 1,2-disubstituted alkenes, the reaction of ,,,-unsaturated phenyl sulfones with aryl iodides under Heck reaction conditions takes place mainly by means of a four-component domino process, involving one unit of the alkene and three units of the aryl iodide, affording substituted 9-phenylsulfonyl-9,10-dihydrophenanthrenes. We report here the results of a computational study on the mechanism of this domino arylation reaction. Based on these results we can explain why vinyl sulfones, unlike other electron-deficient alkenes such as enones, preferentially follow this domino pathway instead of the usual Heck pathway. The key step is a CH activation process in which a five-membered palladacycle is formed. The greater ability of vinyl sulfones, relative to enones, to reach the transition state that leads to the formation of the initial palladacycle makes the difference. Al contrario que los alquenos acíclicos 1,2-disustituidos tradicionalmente utilizados, la reacción de fenil sulfonas ,,, -insaturadas con yoduros de arilo bajo condiciones de reacción de Heck tiene lugar mayoritariamente a través de un proceso dominó de cuatro componentes, en el que participan una unidad de alqueno y tres unidades de yoduro de arilo, dando lugar a 9-fenilsulfonil-9,10-dihidrofenantrenos sustituidos. Aquí se presentan los resultados de un estudio computacional sobre el mecanismo de esta reacción de arilación dominó. De acuerdo con estos resultados se puede explicar por qué en el caso de las vinil sulfonas este camino de reacción predomina sobre la reacción de Heck, al contrario que en el caso de otros alquenos pobres en electrones como las enonas. La etapa clave es un proceso de activación CH en el que se forma un paladaciclo de cinco miembros. La mayor capacidad de las vinil sulfonas en comparación con las enonas para alcanzar el estado de transición que conduce al paladaciclo es la causa fundamental de este comportamiento diferencial. [source] | ||||||||||