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Unsaturated
Terms modified by Unsaturated Selected AbstractsCalculated Enthalpies for Dimerisation of Binary, Unsaturated, Main-Group Element Hydrides as a Means to Analyse Their Potential for Multiple BondingEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 11 2003Hans-Jörg Himmel Abstract Herein, the dimerisation of subvalent, binary, main-group element hydrides with the potential for multiple bonding is studied using both hybrid DFT (B3LYP) and ab initio [MP2 and CCSD(T)] methods. The [2+2] cycloaddition is an important and characteristic reaction of derivatives of ethylene. A comparison of dimerisation reactions for several compounds with the potential for multiple bonding should, therefore, shed light on the properties of these species. Our study includes the hydrides E2H2 (E = B, Al, Ga, N P or As), E2H4 (E = C, Si or Ge) and ENH4 (E = B, Al or Ga) and their dimers. Several isomeric forms of the monomers and dimers have to be considered. The trends within a group and a period are established and the factors responsible for them are discussed. It turns out that, generally, the enthalpies for dimerisation increase for heavier homologues, reflecting that the most important factor is the reduced strength of the E,E bonds in the monomers prior to dimerisation and, to some degree, also the reduced ring strain in the cyclic dimers. The exceptions are the dimerisations of B2H2 and Al2H2, both of which lead to the tetrahedral E4H4 species (E = B or Al). Dimerisation of Al2H2 is associated with a smaller enthalpy than that for the dimerisation of B2H2. Comparisons and analyses are made complicated because of the changes in the structures of the isomeric global minima between homologues. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Synthesis of a Highly Unsaturated, Stable Hydroxy Peroxide: A Yellow [lrarr2] Blue Color-Changing Carotenoid Oxidation Product with Leuco Dye PropertiesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 24 2010He Li Abstract A stable, highly unsaturated hydroxy peroxide was synthesized by reacting a common food color carotenoid with FeCl3 in air. The obtained pale-yellow carotenoid hydroxy peroxide is easily converted into a blue, cationic polyene , then changes back to the yellow compound, showing the same characteristically dichromic properties like polycyclic, aromatic leuco dyes. [source] Organocatalytic Asymmetric Sulfa-Michael Additions to ,,,-Unsaturated Sulfonates,EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 11 2009Dieter Enders Abstract The reactivity of ,,,-unsaturated sulfonates and aromaticthiols in an organocatalyzed sulfa-Michael addition was explored. Bifunctional chiral thiourea catalysts were found to promote the reaction, and the corresponding Michael adducts were afforded in moderate to good yields (24,92,%) and with moderate levels of asymmetric induction (33,64,% ee). This study represents the first use of ,,,-unsaturated sulfonates in a catalytic asymmetric Michael addition. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Highly Enantioselective Michael Addition of Cyclic 1,3-Dicarbonyl Compounds to ,,,-Unsaturated ,-Keto EstersADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 10 2010Xing-Kuan Chen Abstract A highly enantioselective Michael addition of cyclic 1,3-dicarbonyl compounds to ,,,-unsaturated ,-keto esters catalyzed by amino acid-derived thiourea-tertiary-amine catalysts is presented. Using 5,mol% of a novel tyrosine-derived thiourea catalyst, a series of chiral coumarin derivatives were obtained in excellent yields (up to 99%) and with up to 96% ee under very mild conditions within a short reaction time. [source] Highly Enantioselective Michael Addition of ,-Substituted Cyano Ketones to ,,,-Unsaturated ,-Keto Esters using Bifunctional Thiourea-Tertiary Amine Catalysts: An Easy Access to Chiral DihydropyransADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 17 2009Sheng-Li Zhao Abstract An asymmetric Michael addition of ,-substituted cyano ketones to ,,,-unsaturated ,-keto esters to form chiral dihydropyrans catalyzed by a series of ,-amino acid-derived thiourea-tertiary amines is presented. A novel tyrosine-derived thiourea catalyst was identified as the optimal catalyst providing the desired product in 91,95% yields and with 90,96% ee at a low catalyst loading of 2.0,mol%. The utility of the reaction was exemplified by facile conversion of the dihydropyran product into pharmaceutically useful dihydropyridine. [source] Inclusion of Blended Lipid Solutions as Functional Ingredients to Alter the Fatty Acid Profile of Beef PattiesJOURNAL OF FOOD SCIENCE, Issue 7 2010A.C. Lowder Abstract:, Beef patties formulated to contain beef fat, plant oil, and a rosemary extract to increase unsaturated fatty acid content and maintain desirable sensory attributes were compared to control beef patties formulated without plant oils. Treatment patties were formulated to a fat content of 10% or 20% by combining beef trimmings (6% fat) with 4% or 14% addition of a lipid blend. Blends contained 57% beef tallow, 0.3% rosemary extract, and 43% of high oleic safflower oil (SO), olive oil (OO), or corn oil (CO). Lipid oxidation, as measured by TBA values, of treatment patties were similar to control patties after 0 and 3 d of refrigerated (2 °C) storage and up to 56 d of frozen (,10 °C) storage. Cooked lipid blend patties having a fat content of 10% or 20% were similar to or higher than control patties for juiciness and were no different for other sensory attributes evaluated. At fat levels of 10% or 20%, oleic acid (18: 1) in cooked SO patties (46.1% and 50.3%, respectively) and OO patties (43.8% and 48.1%, respectively) was higher than the control (37.3% and 37.6%, respectively). Unsaturated to saturated fatty acid ratios at the 10% or 20% fat levels were higher in SO (1.37 and 1.60, respectively) and CO (1.40 and 1.48, respectively) patties than the control (0.97 and 0.94, respectively). Beef patties manufactured with varying lipid blends increased unsaturated fatty acid content and were similar in physical characteristics and sensory attributes of all beef patties formulated without lipid blends. Practical Application:, The development of healthier beef products that will be more appealing to consumers has long been an industry goal. The authors believe that lipid blends such as the one used in this study could be used to create such products, not only in the form of beef patties, but any number of processed meat products. Because the materials and equipment used to create the lipid blends in this study are widely available, their incorporation into meat products would represent a small capital investment. This is an important factor in bringing a reasonably priced, healthier product to consumers. [source] Food wrapping by females of the European Beewolf, Philanthus triangulum, retards water loss of larval provisionsPHYSIOLOGICAL ENTOMOLOGY, Issue 2 2008GUDRUN HERZNER Abstract Females of the European beewolf, Philanthus triangulum F. (Hymenoptera, Crabronidae), embalm the provisions of their larvae, paralyzed honeybees, with a secretion from a postpharyngeal gland prior to oviposition. This food wrapping is known to delay fungus infestation of the prey. In the present study, the hypothesis that the food wrapping has an additional function, namely the prevention of prey desiccation, is tested. Water loss of paralyzed but unembalmed honeybees and embalmed honeybees is measured and the composition and quantity of their cuticular hydrocarbons analyzed by coupled gas chromatography,mass spectrometry. Water loss is significantly lower in embalmed compared with unembalmed bees. This might have important advantages for the larvae under the warm and dry conditions that prevail in some brood cells. The embalming by beewolf females increases the total amount of hydrocarbons on the surface of the bees by almost ten-fold. Moreover, the proportion of unsaturated and short-chained hydrocarbons is significantly increased. Unsaturated and short-chain hydrocarbons are usually less effective against water loss, so the increased protection against water loss appears to be mediated mainly by the thickness of the hydrocarbon layer. [source] ChemInform Abstract: Single-Step Symmetrical Double Alkylation of ,,,-Unsaturated ,-Lactams via Magnesium "Ate" Complexes.CHEMINFORM, Issue 49 2009Jacek G. Sosnicki 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: Catalytic, Asymmetric Michael Reactions of Cyclic Diketones with ,,,-Unsaturated ,-Ketoesters.CHEMINFORM, Issue 40 2009Michael A. Calter 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: Reaction of N, -Benzylserotonin with ,,,-Unsaturated and Aryl Aldehydes in the Presence of a Base.CHEMINFORM, Issue 27 2009Koji Yamada 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: An Easy Approach to ,,,-Unsaturated ,-Thiolactams via a RCM and Thionation One-Pot Procedure.CHEMINFORM, Issue 15 2009Jacek G. Sosnicki 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: Highly Enantioselective Friedel,Crafts Reaction of 4,7-Dihydroindoles with ,,,-Unsaturated ,-Keto Esters by Chiral Broensted Acids.CHEMINFORM, Issue 9 2009Mi Zeng 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: Synthesis of ,-Alkylidene ,,,-Unsaturated ,-Lactones by Ring-Closing Metathesis: Application to the Synthesis of the C1,C8 Subunit of Biselide E.CHEMINFORM, Issue 8 2009Anne-Frederique Salit 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: Highly Stereoselective Oxy-Michael Additions to ,,,-Unsaturated ,-Keto Esters: Rapid Enantioselective Synthesis of 3-Hydroxybutenolides.CHEMINFORM, Issue 30 2008Xin Xiong 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] Diastereoselective Construction of Indolo[2,3-a]quinolizidine Skeleton by Cycloaddition Reaction of 3,4-Dihydro-,-carbolines with ,,,-Unsaturated ,-Ketoesters.CHEMINFORM, Issue 39 2007Kazuhiro Nagata 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] Diversely Substituted Sugar-Linked ,,,-Unsaturated ,-Lactones from Sugar-Derived Baylis,Hillman Adducts via a RCM.CHEMINFORM, Issue 24 2007Palakodety Radha Krishna 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] Selective 1,2- vs 1,4-Addition of N-Arylphosphazenes to ,,,-Unsaturated ,-Ketoesters.CHEMINFORM, Issue 23 2007Synthesis of Quinolinecarboxylates. 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] Syntheses of Highly Functionalized ,,,-Unsaturated-,-amino Acids.CHEMINFORM, Issue 11 2007Siyuan Chen 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] Enantioselective Scandium-Catalyzed Vinylsilane Additions: A New Approach to the Synthesis of Enantiopure ,,,-Unsaturated ,-Hydroxy Acid Derivatives.CHEMINFORM, Issue 1 2007David A. Evans 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] Efficient Synthesis of 3-Arylaminopyrroline-2-ones by the Tandem Reaction of Anilines and ,,,-Unsaturated ,-Ketoesters.CHEMINFORM, Issue 52 2006Yan-Chao Wu 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] An Efficient Synthesis of Achiral and Chiral Cyclic Dehydro-,-Amino Acid Derivatives Through Nucleophilic Addition of Amines to ,,,-Unsaturated ,-Keto Esters.CHEMINFORM, Issue 41 2006Francisco Palacios 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] Synthesis and Biological Properties of New ,-Methylene-,-butyrolactones and ,,,-Unsaturated ,-Lactones.CHEMINFORM, Issue 31 2006Francesca Cateni 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] Diastereoselective Addition of Nitro Compounds to ,,,-Unsaturated ,-Butyrolactones.CHEMINFORM, Issue 17 2006Giovanni B. Rosso 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] Sc(OTf)3 -Catalyzed Indolylation of 1,2-Allenic Ketones: Controlled Highly Selective Synthesis of ,-Indolyl-,,,-Unsaturated (E)-Enones and ,,,-Bisindolyl Ketones.CHEMINFORM, Issue 10 2006Shengming Ma 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] ,,,-Unsaturated ,-Diketones by Acylation of Ketones.CHEMINFORM, Issue 5 2006Alan R. Katritzky Abstract For Abstract see ChemInform Abstract in Full Text. [source] Mn(III)-Based C,C Bond Formation: Regioselective ,,-Allylation of Various ,,,-Unsaturated, ,- and ,-Alkoxy ,,,-Unsaturated Ketones.CHEMINFORM, Issue 49 2005Cihangir Tanyeli Abstract For Abstract see ChemInform Abstract in Full Text. [source] ,,,-Unsaturated ,,-Halomethylsulfones: Prepackaged Ramberg,Baecklund Reagents for Tandem Synthetic ProcessesCHEMINFORM, Issue 34 2005Eric Block Abstract For Abstract see ChemInform Abstract in Full Text. [source] A Concise Synthesis of Highly Functionalized ,,,-Unsaturated ,-Butyrolactones Through Ring Contraction of 2H-Pyran-2-ones.CHEMINFORM, Issue 46 2004Diptesh Sil Abstract For Abstract see ChemInform Abstract in Full Text. [source] Preparation of ,,,-Unsaturated ,-Keto Aldehydes and New Tetronic Acid and Pyridazine Derivatives by Oxidative Transformations of Alkoxyallene-Based Dihydrofurans.CHEMINFORM, Issue 43 2004Oliver Floegel 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. 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