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Showing 1 to 15 of 15 for “"Asymmetric syntheses"”.
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Asymmetric syntheses of anthraquinonyl C-glycosides
Syntheses of C2-anthraquinone aldehydes from the commercially available anthrarufin 11 have been investigated. A synthesis of the ketoaldehyde 5 in nine steps and 73% overall yield was achieved. Syntheses of 5 exploiting selective oxidations of either a C-bound allyl group via Wacker oxidation to …
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Asymmetric Syntheses With (-)-Sparteine-Complexed Benzylic and Allylic Organolithium Reagents
The kinetic resolution of racemic cyclic unsaturated esters with the organolithium intermediates derived from lithiation of N-Boc- N-(p-methoxyphenyl)cinnamylamine with n -BuLi/(-)-sparteine was investigated. Kinetic resolution in conjugate addition reactions with alpha,beta-unsaturated lactones …
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Novel syntheses by directed lithiations of N-Boc benzylamines and cyclopropylamines
… of these substrates. We have achieved the syntheses of highly enantioenriched benzylic $\alpha$-substituted N-Boc secondary amines using RLi/(-)-sparteine. Extension of this chemistry to asymmetric syntheses of both enantiomers of primary $\alpha$-substituted benzylamines and …
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Phosphate Tether-mediated Approaches for the Syntheses of Complex Polyols, Natural Products and Related Analogs
… new synthetic strategies, allowing for efficient asymmetric syntheses of complex biologically active natural products, natural product analogs, and pharmaceutical agents is a long-standing goal for synthetic chemists. In particular, divergent strategies that allow the generation of multiple …
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Asymmetrische Synthese von hoch substituierten delta -Lactonen : Synthese der Prelactone B und V, von Simplacton B und von Massoialacton
The asymmetric syntheses of prelactone B und V, simplactone B, massoialactone and of related Delta-lactones were carried out in this work. The RAMP-hydrazone of 2,2-dimethyl-1,3-dioxan-5-one was chosen as starting material for the synthesis of the 4-hydroxy-5,6-alkyl and 4-hydroxy-5-alkyl …
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The asymmetric synthesis of (2S,3R)-capreomycidine and the total synthesis of capreomycin IB
An efficient and asymmetric synthesis of the non-proteinogenic amino acid (2S,3R)-capreomycidine is presented. The synthesis features a novel aluminum enolate-aldimine reaction with a chiral glycinate, which sets both stereocenters. A concise and high-yielding approach to the unnatural amino acid …
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Experimental and Computational Studies in Bioorganic and Synthetic Organic Chemistry
… the strongest cationâ Ï donor. We reported the asymmetric syntheses of tryptophan regioisomers in which the amino acid side chain is attached at different position of the indole moiety. These new tryptophan regioisomers can effect a different mode of cationâ Ï interaction. In nature, dramatic …
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EXPLORATIONS IN MEDIUM-RING ETHER SYNTHESIS VIA UMPOLUNG HETEROATOM ACTIVATION: TOTAL SYNTHESIS, METHODS DEVELOPMENT, AND REAGENT SYNTHESIS
… to medium-sized cyclic ethers, the 11-step total syntheses of Heliannuols D and A was accomplished in the most concise and highest yielding asymmetric syntheses to date. The divergent synthetic strategy has also enabled access to a library of unnatural analogues which are being screened for …
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Asymmetric Synthesis of 1,3-Amino Alcohols and Tropinone Derivatives From Enantiopure Sulfinimines
… The intent of this research is to the develop asymmetric syntheses of piperidine-containing syn and anti 1,3-amino alcohols as well as tropinone and tropane-containing derivatives using sulfinimines (N-sulfinyl imines) as precursors for acid-catalyzed cascade cyclizations. Chiral N-sulfinyl …
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Asymmetrische Totalsynthese des hochwirksamen Prostacyclin-Analogons Cicaprost
An asymmetric synthesis of cicaprost and a formal asymmetric synthesis of isocicaprost by a new strategy are described. The key steps of theses syntheses are the coupling of chiral bicyclic C6-C14 alkyne building blocks with a chiral C15-C20 omega-side chain Weinreb-amide building block at the …
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Asymmetrische Totalsynthese von 16(S)-Iloprost und 3-Oxa-16(S)-Iloprost mittels der Azoen-Strategie
… describes completely stereocontrolled asymmetric syntheses of 16S-iloprost and of 16S-3-oxa-iloprost by a azoene strategy. As Ilomedin and Ventavis registrated iloprost (1:1 mixture of diastereomers at C16) serves as a drug against ischemic heart disease, peripheral vascular disease and …
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Total Syntheses of (+)-Geldanamycin, (-)-Ragaglitazar, and (+)-Kurasoin A and Phase-Transfer-Catalyzed Asymmetric Alkylation
… formation of GA and future synthetic analogs. Asymmetric glycolate alkylation has been developed using phase-transfer-catalysis (PTC). Diphenylmethoxy-2,5-dimethoxyacetophenone with trifluorobenzyl cinchonidinium catalyst and cesium hydroxide provided alkylation products at —35 °C in high yield …
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Asymmetrische Synthese ausgehend von allylischen Sulfoximinen: neuartige Gamma-Aminosäuren und cyclische Aminosulfoxonium Ylide
… the versatile sulfoximine chiral auxiliary for asymmetric syntheses was clearly demonstrated by means of described examples.
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Syntheses, bioactivities and conformations of peptidomimetics containing 2,3-methanoamino acids
Asymmetric syntheses of E- and Z-2,3-methanomethionine (ie E- and Z-cyclo-Met), protected Z-2,3-methanoarginine, and Z-2,3-methanoaspartic acid derivatives have been developed. These functionalized 2,3-methanoamino acids were prepared from a common intermediate: 1- ((tert-butoxy)carbonyl) …