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Showing 1 to 20 of 24 for “"1,4-addition"”.
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1,4 addition of Grignard Reagents to 9-Phenanthryl Ketones
Made available in DSpace on 2014-12-05T19:36:31Z (GMT). No. of bitstreams: 1 0019877.pdf: 3599809 bytes, checksum: 8f048b2f4c95849651718b6ef4819155 (MD5) Previous issue date: 1956
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Asymmetrische Totalsynthese von 13,14-Dinor-inter-p-phenylencarbacyclin mittels konjugierter 1,4-Addition an ein Azoen
… ketones, a suitable substrate for conjugate additions with organocopper compounds. The conjugate addition to the azoene succeeded with phenyl copper as well as with the aryl copper compound containing the complete omega-side chain fragment. The conjugate addition delivered the alpha-arylated …
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Entwicklung neuer chiraler N-heterocyclischer Carbenliganden auf Aminosäurebasis und deren Einsatz in der asymmetrischen Metathese und 1,4-Addition
… NHC-Liganden in der asymmetrischen 1,4-Addition. Als Testsystem wurde die Umsetzung von Cyclohexenon mit Diethylzink gewählt und unter Verwendung von Ligand L1 optimiert. Fünf weitere neue NHC-Liganden wurden hergestellt, mit den optimierten Reaktionsbedingungen getestet und Rückschlüsse …
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Asymmetric Syntheses With (-)-Sparteine-Complexed Benzylic and Allylic Organolithium Reagents
… investigated. Kinetic resolution in conjugate addition reactions with alpha,beta-unsaturated lactones proceed with retention of configuration to provide 1,4-addition products with three contiguous stereogenic centers with high stereoselectivities. In all cases of a 1,4-addition selectivity …
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Novel Conjugate Additions and Cyclizations on Multiyne Systems
… seven chapters focusing on extended conjugation addition chemistry and different modes of cyclization to synthesize important and unique heterocycles including natural products and biomolecules. Chapter 1 provides a novel route for the synthesis of 4-pyrones with broader substrate scope and …
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A novel, versatile D-BCD steroid construction strategy, illustrated by the total syntheses of estrone and desogestrel
… desogestrel and estrone, utilizing a 1,4 addition/alkylation process to install the correct stereochemistry at C8, C13 and C14 in a single-pot operation. The racemic total synthesis of desogestrel includes a successful domino anionic cyclisation leading to the formation of the steroid C …
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(--)-Sparteine Mediated Asymmetric Synthesis Through Conjugate Addition of Allylic and Benzylic Organolithium Species: Development of a Methodology and Its Application Toward a Total Synthesis
… gamma-lactams in high yield. In addition, conjugate addition of the allylic organolithium species with N-protected 4-pyridones provides high yields of the corresponding 1,4-addition adduct with high enantiomeric ratios (ers). The reaction is believed to proceed through an N-acyl …
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Applications of nitroalkene (4+2); cycloaddition chemistry. The asymmetric synthesis of substituted pyrrolidines and the total synthesis of mesembrine
… 1-nitroalkenes has been developed. Conjugate 1,4-addition of zinc cuprates (RCu(CN)ZnI) to easily obtained (E)-1-nitroalkenes, followed by trapping with phenylselenenyl bromide, and subsequent oxidative elimination afforded the corresponding 2,2-disubstituted 1-nitroalkenes in 76-88% yield as E/Z …
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Asymmetrische C-C-Knüpfungsreaktionen mit lithiierten Alkyl- und Allylsulfoximinen
… This Michael-type reaction leads to the 1,4-addition products and the so-called tandem products. These tandem products are formed with high diastereoselektivity by addition of one molecule of sulfoximine with two molecules of ester. It was not possible to isolate the pure compounds because …
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Neue Glycooxazolidin-2-on-Auxiliare für die stereoselektive Synthese
… Diels-Alder Reaktionen, sowie bei der 1,4-Addition von Dimethyl- und Diethylaluminiumchlorid an ungesättigte N-Acyl-Derivate untersucht. Dabei konnte gezeigt werden, dass drei der vier neuen Verbindungen die an ein chirales Auxiliar gestellten Anforderungen erfüllen konnten. Zudem wiesen …
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Towards the total synthesis of gambieric acid A
… of the methyl group of the F ring using a 1,4 addition with a cuprate reagent to an a,b-unsaturated lactone is discussed in detail. In addition, efficient introduction of the side chain to the J ring using a cyclic siloxane using a model system is also reported, after the exploration of ten …
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Theoretical study of fullerences and carbon nanotubes
… III analyzes two possible patterns of fluorine addition to single wall carbon nanotube that have been proposed as 1,2 and 1,4 addition. Semi-empirical calculations indicate that the 1,4 isomer is lower in energy. Fluorine atoms prefer to grow along the tube for the 1,2 isomer whereas for the 1,4 …
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IMPROVING THE SCOPE AND UNDERSTANDING OF THE SYMMETRIC AND ASYMMETRIC SUZUKI COUPLING REACTION
… application in a rhodium-catalysed 1,4-addition reaction. Experimental studies of asymmetric Suzuki cross-couplings towards axially chiral biaryl products have also been detailed. Model reactions towards configurationally stable biaryl products were found to undergo a successful chiral …
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Development of novel methodologies utilizing quaternary ammonium salts as catalysts
… the development of a fluoride-promoted conjugate addition of sulfur-stabilized carbanion nucleophiles to α,β-unsaturated ketones and esters. This reaction was achieved using a substoichiometric amount of TBAF, resulting in high yields on the desired 1,4-addition product. The addition of …
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Novel addition reactions of some benzopyrans
… 2-(2-hydroxybenzoyl)-2-penten-4-ynonitriles. The addition of lithium dipent-1-ynylcuprate to chromone-3-carbonitrile gave a remarkable new compound Z-2-[6-propyl-8-oxo-6H,8H-bis[1]benzopyrano[2,3-b:3.4'e]pyridin-6-yl]oct-2-en-4-ynonitrile. The 1,4-addition of dialkynylcuprates to …
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Cyclische Alpha- und Ortho-Lithio-S-Phenyl-Sulfoximine : Synthese, Funktionalisierung und Umlagerung
… for the use as ligands in the asymmetric 1,4-addition. This aim was tried to achieve through synthesis of different substituted cyclic sulfoximines for the use as chiral nontransferable ligands in the stoichometric conjugate addition. Another topic was the synthesis of sulfoximines which could …
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Aplicaciones derivadas de la fotoquímica de O-aciloximas
… kind. When the radical participates in a 1,4- addition to alkynylcarbene complexes 5-aza-1-metalla-1,3,5-hexatriene where obtained, while the 1,2 addition led to azepines. In Chapter 5, the synthesis of more complex acyloximes to give new nitrogen containing heterocyclic compounds by the …
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Πορείες συνθέσεως ενώσεων με βιολογικό ενδιαφέρον από 2Η-πυραν-3(6Η)-όνες
… a) The chemistry of 2H-pyran-3(6H)-ones. b) 1,4-addition (Michael) to 2H-pyran-3(6H)-ones. c) Immunostimulants. d) Sympathomimetic amines, neurotransmitters. Part II contains five chapters and deals with the results of the present work. More specifically describes: i) The synthesis of …
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Asymmetrische Totalsynthese von 16(S)-Iloprost und 3-Oxa-16(S)-Iloprost mittels der Azoen-Strategie
… One of the major key steps is the conjugate 1,4 addition of an C13-C20 organocopper building block to the bicyclic C6-C12 azoene with formation of the corresponding hydrazone in 84% yield. The E-Isomer of 16S-iloprost was obtained in 11 steps with an overall yield of 5%. 3-Oxa-16S-iloprost was …
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Synthesis and application of chiral dienes and chiral imidates as ligands for transition metal catalysis
… were tested in the rhodium(I)-catalyzed 1,4-addition of phenylboronic acids to cyclic enones (up to 96% ee) and α-acetamido acrylic ester and in the rhodium(I)-catalyzed 1,2-addition of phenylboronic acids to benzaldehydes (up to 48% ee). We introduced chiral imidates as a novel …
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