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Showing 1 to 20 of 34 for “"1,2-Addition"”.
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Asymmetric synthesis of trisubstituted isoindolines and tetrahydropalmatine via tandem 1,2-addition-cyclisation
… isoindolines via a tandem 1,2-addition/cyclisation process was developed. After condensation of SAMP with o-phthalic dicarboxaldehyde, the remaining aldehyde functionality was transformed into different alkenes by Horner-Wadsworth-Emmons reaction. Addition of a organolithium …
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Totalsynthese von (+)-2-epi-Deoxoprosopinin und neue Hydrazin-Harze für die organische Festphasensynthese
… (de,ee >=96%) is described. As key steps the 1,2-addition of a dodecyl nucleophile to an aldehyde-SAMP hydrazone and the a -alkylation of 2,2-dimethyl-1,3-dioxan-5-one SAMP hydrazone were employed to generate two of the three stereogenic centers. Creation of the third stereogenic center was …
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Asymmetric synthesis of lignans and of α-heteroaryl)alkylamines employing the SAMP-/RAMP-hydrazone method
… based on nucleophilic 1,2-addition of heteroarenyllithium species to SAMP-/RAMP-hydrazones, has been developed. Moreover the novel methodology was successfully applied to the synthesis of biologically interesting compounds such as a-aminoacids and b-aminosulfones.
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Asymmetrische Synthese von Gamma-Hydroxy-Alpha-Aminosäuren, 1,3-Aminoalkoholen und 2-Amino-3-Phosphonopropionsäure
… aldol reaction. After protection, 1,2-addition and cleavage of the chiral auxiliary the products could be isolated over five steps in 30 to 54% overall yield and diastereomeric excesses of 78 to 84% and enantiomeric excesses over 96%. Furthermore we developed a hydrazone Strecker-method …
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Reaktionsweisen eines Tetraaryldigermens: Synthese des ersten Tetragermabuta-1,3-diens
… strukturelle Integrität in der Lösung durch 1,2-Addition von HN 3 oder durch [2+1]-Cycloaddition von Diazomethan-Derivaten zu dem Digermiridin-Ringsystem nachgewiesen. Nur bei verschärften Reaktionsbedingungen zerfiel das Digermen in Germylen-Moleküle, die mit einem ortho-Benzochinon abgefangen …
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Computational Studies of Selected Ruthenium Catalysis Reactions.
… carbon-hydrogen bond activation by 1,2-addition/reductive elimination pathways appropriate to catalytic hydrogen/deuterium exchange, and the possible intermediacy of highly coordinatively unsaturated (e.g., 14-electron) ruthenium complexes in catalysis. The calculations indicate a …
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Neue chirale Triazoliumsalze in der Carben-katalysierten intramolekularen gekreuzten Benzoin-Reaktion
… has been developed. After a simple 1,2-addition the corresponding tertiary alcohols can be obtained which are structural motifs in many bioactive natural products such as the coumarins smyrindiol and vaginidiol.
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Asymmetrische Synthese von Stigmolon und Untersuchungen zur asymmetrischen Synthese von (-)-Cytoxazon und Galbonolid A und B
… and costs. Through alpha-alkylation and 1,2-addition of p-anisyl lithium to SAMP-hydrazones, the hydrazines were achieved as diastereo- and enantiomerically pure compounds with good yields. Syntheses of 3-SMP substituted cis-oxazolidin-2-ones were successfully achieved with very good yields …
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Untersuchungen zur diastereo- und enantioselektiven Synthese von Matsuon und asymmetrische Synthese von anti-1,2-Sulfanylaminen
… with various electrophiles and the following 1,2-addition to the C-N double bond using different alkylcerium nucleophiles. After removal of the auxiliary by cleavage of the N-N-bond the resulting amines could be isolated or converted to the corresponding benzyl carbamates.
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An investigation of the chemistry of lithiotriphenylphosphineacetylmethylene
… with 2-cyclohexene-1-one gave the 1,2-addition product, although it could not be completely purified. Attempts to form potassiotriphenylphosphineacetylmethylene by means of potassium amide in liquid ammonia gave the unexpected product, acetonyldiphenylphosphine oxide. An earlier …
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Bicyclische Triazoliumsalze als Präkatalysatoren in der asymmetrischen Benzoin- und Acyloinkondensation und asymmetrische Synthese von Oxazolidin-2-onen
… step reaction sequence of alpha-alkylation, 1,2-addition with subsequent carbamate protection, cyclization and concluding with cleavage of the auxiliary the title compounds are obtained in moderate yields and in excellent diastereo- and enantiomeric excesses (de = 88 - >96%, ee = >96%). The …
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Direct ⍺-C–H Functionalisation of Cyclic Alkylamines
… iminium ion formation followed by the 1,2-addition of carbon-based nucleophiles. Key to this strategy was the selective formation of endo-iminium ions from six-membered N-heterocycles, achieved via α-C–H elimination from the corresponding cyclic tertiary alkylamine N-oxides. The subsequent …
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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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Exploring Nickel Catalysis in Carbonyl and Alcohol Addition Reactions
The nucleophilic addition of organomagnesium/lithium reagents to aldehydes and ketones has long enabled the synthesis of valuable alcohol derivatives; however, these types of transformations are often plagued by poor functional group tolerance and require harsh reaction conditions. The direct …
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Polarity Inversion in Silicon and Phosphorus Compounds
… silylenes will be described. This cycloaddition initiates stepwise deoxygenation by silicon(II), and the application of this rare mode of reactivity to a room-temperature variant of the Cadogan reaction will be detailed. In a second section, tetragonal phosphorus(V) cations supported by …
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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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Neue optisch aktive Phosphoniumsalze als Phasentransferkatalysatoren sowie die Verwendung der korrespondierenden Phosphane in der asymmetrischen Katalyse
… hydrovinylation, rhodium-catalyzed 1,2-addition and ruthenium catalyzed transfer hydrogenation.
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Asymmetrische Synthese von 1,3-Aminoalkoholen und deren Anwendung zur Synthese von Azetidinen und 1-Azabicyclen
… were synthesized using a nucleophilic 1,2-addition to the C=N-double bond of the SAMP/RAMP hydrazones with organolithium- or organocer-reagents. Second, an epimerization-free reductive N,N-bond-claverage with BH3-THF-complex was performed. Lastly, N-protection with chloroformic acid benzyl …
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