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Ethyl Vinyl Ketone (ethyl + vinyl_ketone)
Selected AbstractsChemInform Abstract: Aza-Baylis,Hillman Reaction of Salicyl N-Tosylimines with Methyl Vinyl Ketone, Ethyl Vinyl Ketone or Phenyl Vinyl Ketone.CHEMINFORM, Issue 5 2008Ming-Juan Qi 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] Ruthenium,Lewis Acid Catalyzed Asymmetric Diels,Alder Reactions between Dienes and ,,,-Unsaturated KetonesCHEMISTRY - A EUROPEAN JOURNAL, Issue 12 2007Jenny Rickerby Dr. Abstract The complex [Ru(Cp)(R,R -BIPHOP-F)(acetone)][SbF6], (R,R)- 1,a, was used as catalyst for asymmetric Diels,Alder reactions between dienes (cyclopentadiene, methylcyclopentadiene, isoprene, 2,3-dimethylbutadiene) and ,,,-unsaturated ketones (methyl vinyl ketone (MVK), ethyl vinyl ketone, divinyl ketone, ,-bromovinyl methyl ketone and ,-chlorovinyl methyl ketone). The cycloaddition products were obtained in yields of 50,90,% and with enantioselectivities up to 96,% ee. Ethyl vinyl ketone, divinyl ketone and the halogenated vinyl ketones worked best and their reactions with acyclic dienes consistently provided products with >90,% ee. ,-Chlorovinyl methyl ketone performed better than ,-bromovinyl methyl ketone. The reaction also provided a [4.3.1]bicyclic ring system in 95,% ee through an intramolecular cycloaddition reaction. Crystal structure determinations of [Ru(Cp)((S,S)-BIPHOP-F)(mvk)][SbF6], (S,S)- 1,b, and [Ru(Cp)((R,R)-Me4BIPHOP-F)(acrolein)][SbF6], (R,R)- 2,b, provided the basis for a rationalization of the asymmetric induction. [source] Dendritic Chiral Phosphine Lewis Bases-Catalyzed Asymmetric Aza-Morita,Baylis,Hillman Reaction of N -Sulfonated Imines with Activated OlefinsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 1 2008Ying-hao Liu Abstract A series of polyether dendritic chiral phosphine Lewis bases was synthesized, and successfully applied to the asymmetric aza-Morita,Baylis,Hillman reaction of N -sulfonated imines (N -arylmethylidene-4-methylbenzenesulfonamides) with methyl vinyl ketone (MVK), ethyl vinyl ketone (EVK), and acrolein to give the adducts in good to excellent yields along with up to 97,% ee, which are more effective than our previously reported original chiral phosphine Lewis bases. In addition, the dendrimer-supported chiral phosphine Lewis bases can be easily recovered and reused. [source] Mono and double polar [4 + 2+] Diels,Alder cycloaddition of acylium ions with O -heterodienesJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 2 2002Eduardo C. Meurer Abstract Gas-phase reactions of acylium ions with ,,,-unsaturated carbonyl compounds were investigated using pentaquadrupole multiple-stage mass spectrometry. With acrolein and metacrolein, CH3,C+O, CH2CH,C+O, C6H5,C+O, and (CH3)2N,C+O react to variable extents by mono and double polar [4 + 2+] Diels,Alder cycloaddition. With ethyl vinyl ketone, CH3,C+O reacts exclusively by proton transfer and C6H5,C+O forms only the mono cycloadduct whereas CH2CH,C+O and (CH3)2N,C+O reacts to great extents by mono and double cycloaddition. The positively charged acylium ions are activated O -heterodienophiles, and mono cycloaddition occurs readily across their C+O bonds to form resonance-stabilized 1,3-dioxinylium ions which, upon collisional activation, dissociate predominantly by retro-addition. The mono cycloadducts are also dienophiles activated by resonance-stabilized and chemically inert 1,3-dioxonium ion groups, hence they undergo a second cycloaddition across their polarized CC ring double bonds. 18O labeling and characteristic dissociations displayed by the double cycloadducts indicate the site and regioselectivity of double cycloaddition, which are corroborated by Becke3LYP/6,311++G(d,p) calculations. Most double cycloadducts dissociate by the loss of a RCO2COR1 molecule and by a pathway that reforms the acylium ion directly. The double cycloadduct of the thioacylium ion (CH3)2N,C+S with acrolein dissociates to (CH3)2N,C+O in a sulfur-by-oxygen replacement process intermediated by the cyclic monoadduct. The double cycloaddition can be viewed as a charge-remote type of polar [4 + 2+] Diels,Alder cycloaddition reaction. Copyright © 2001 John Wiley & Sons, Ltd. [source] Ruthenium,Lewis Acid Catalyzed Asymmetric Diels,Alder Reactions between Dienes and ,,,-Unsaturated KetonesCHEMISTRY - A EUROPEAN JOURNAL, Issue 12 2007Jenny Rickerby Dr. Abstract The complex [Ru(Cp)(R,R -BIPHOP-F)(acetone)][SbF6], (R,R)- 1,a, was used as catalyst for asymmetric Diels,Alder reactions between dienes (cyclopentadiene, methylcyclopentadiene, isoprene, 2,3-dimethylbutadiene) and ,,,-unsaturated ketones (methyl vinyl ketone (MVK), ethyl vinyl ketone, divinyl ketone, ,-bromovinyl methyl ketone and ,-chlorovinyl methyl ketone). The cycloaddition products were obtained in yields of 50,90,% and with enantioselectivities up to 96,% ee. Ethyl vinyl ketone, divinyl ketone and the halogenated vinyl ketones worked best and their reactions with acyclic dienes consistently provided products with >90,% ee. ,-Chlorovinyl methyl ketone performed better than ,-bromovinyl methyl ketone. The reaction also provided a [4.3.1]bicyclic ring system in 95,% ee through an intramolecular cycloaddition reaction. Crystal structure determinations of [Ru(Cp)((S,S)-BIPHOP-F)(mvk)][SbF6], (S,S)- 1,b, and [Ru(Cp)((R,R)-Me4BIPHOP-F)(acrolein)][SbF6], (R,R)- 2,b, provided the basis for a rationalization of the asymmetric induction. [source] | ||||||||||