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Showing 1 to 20 of 35 for “"Phosphoramidite"”.
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Chirale Phosphortriamide und Phosphin-Phosphoramidite als Liganden für die asymmetrische Katalyse
… structures (phosphorus triamides or phosphine-phosphoramidites respectively) are taken into account. These lead structures are varied via modular synthetic routes. In summary 12 new chiral ligands – 9 phosphorus triamides and 3 phosphine-phosphoramidites – have been synthesised and applied to …
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Mechanistic studies on iridium catalyzed allylic substitution
… substitution reactions catalyzed by iridium phosphoramidite complexes revealed that the active catalyst is generated through a base assisted cyclometalation of the phosphoramidite to form five-membered iridacycle. A mechanism for the reaction was proposed based on a series of kinetic …
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(A). Regulation of B-/Z-DNA transition in modified oligonucleotides; (B). Synthesis of cationic BODIPY analogues for antimicrobial and anticancer applications
… sequence in a site-specific manner through the phosphoramidite chemistry-based solid phase synthesis to investigate the impact of this modification on the B→Z-DNA transition. Circular dichroism study showed that the incorporation of a single LNA-dG unit into d(CG)6 at internal positions …
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Rhodium-katalysierte, asymmetrische Synthese: Ligandendesign und Methodik
… the use of monodentate ligands such as the phosphoramidite MonoPhos™ led diastereoselectively to the endo-diastereomer with up to 54% ee. Initial experiments with bidentate phosphoramidite-phosphite derivatives of hydroxyproline provided promising results, giving the exo-diastereomer …
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Novel nucleotide analogues for forming stable DNA triple helices
… be formed by the natural base T. Four modified phosphoramidite monomers, meta-aminophenyl-modified analogues of the bicyclic nucleosides, (2,3H)-furano[2,3-d]pyrimidin-2(7H)-one and N-methyl-(2,3H)-pyrrolo- [2,3-d]pyrimidin-2(7H)-one, were synthesised to address this potential hydrogenbonding …
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Towards the synthesis of ferrocene nucleic acids
… into oligonucleotide strands, using solid state phosphoramidite DNA synthesis techniques, and characterised using MALDI-ToF Mass Spectrometry. CD and Tm studies were also carried out. Synthetic strategies towards chiral ferrocenes, via intermediates with groups consisting of protected alcohols or …
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Synthesis and Reactivity of Electroactive Carbon Sulfide Ligands and Studies on Modifications of Nucleic Acids
… in a new method with solid-phase phosphoramidite oligonucleotide synthesis, a mono-, di-, tri-, and tridecanucleotide of DNA with one phosphoroselenoate modification as well as a dinucleotide of RNA modified with one phosphoroselenoate were synthesized. The utility of phosphate …
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Site-Specific Labelling of Nucleic Acids by Catalyst-Free 1,3-Dipolar Cycloadditions
… blocks generated by NOAC. Three isoxazole phosphoramidites were prepared. Following in situ generation of the nitrile oxides from 1,2-, 1,3- or 1,4-disubstituted hydroxyethoxybenzaldehyde oximes and highly regioselective cycloadditions to a simple alkyne, the isomeric isoxazoles were …
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Chemical synthesis of DNA and RNA containing thio-substituted bases and their post-synthetic modifications
… However, design and synthesis of a proper phosphoramidite monomer for a new modified nucleoside are always difficult tasks even for a skilful chemist. Thus an alternative method (post-synthetic method) has been invented to overcome the difficulties. This was achieved by incorporation of …
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Photoelectrochemical array platform for genomic scale DNA synthesis
… Photoelectrochemically patterned microarrays of phosphoramidite dye were produced with spot sizes of 100 um. This technology holds the potential for lowest cost per base pair of DNA produced over alternative microarray technologies, and may prove to be useful in de novo synthesis of large DNA …
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Delivery and stability of antisense oligonucleotide conjugates in vitro
… with the cell membrane. A mono-mannose phosphoramidite derivative was designed and synthesised and a mono-mannose ODN conjugate synthesised by standard phosphoramidite chemistry. Delivery of this conjugate was enhanced to RAW264.7 and J774 macrophage cell lines via a mechanism of …
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Synthesis of triplex-forming oligonucleotide conjugates of the anticancer drug temodal
… of the triplexes studied. The synthesis of a phosphoramidite derivative of mitozolomide enabled direct incorporation of this reagent into a model sequence during DNA synthesis. After cleavage and deprotection of the TFO-drug conjugate, the 5'-end mitozolomide residue was found to have …
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Advancements in the synthesis of distorted tricoordinate phosphorus compounds and their use as platforms in reductive chemistries
… of both hydrazine and hydrazones by a distorted phosphoramidite and initial results in the use of these phosphoranes as platforms for hydrogen atom transfer chemistry. Chapter five presents a unique reaction in the formation of an oxazaphosphole that shows promise to allow for dearomatiztion of …
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ENZYME-LIKE DNA CATALYST DESIGN
… catalysts at site-specific AP sites without phosphoramidite synthesis. This modular platform enables rapid preparation of DNA catalysts and delivers highly enantioselective Friedel–Crafts and atroposelective reactions with low catalyst loading and high turnover. The work further demonstrates …
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Genomic consequences of DNA oxidation by peroxynitrite
… and incorporated into an oligonucleotide by the phosphoramidite method. In the second study, the genotoxic and mutational properties of 2-aminoimidazolone and 5-guanidino-4-nitroimidazole were determined in wild-type uninduced and SOS-induced E. coli.
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Regioselektive und enantioselektive allylische Substitution katalysiert durch Iridiumkomplexe
… optimiert und neue Substrate getestet wurden. Phosphoramidite erwiesen sich als effektivste Liganden in Bezug auf Reaktivität und Regioselektivität. Mit diesen Liganden konnten Regioselektiviäten von 99:1 und Enantioselektivitäten von bis zu 94 ee für alkylsubstituierte Substrate erzielt …
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Entwicklung einer Synthesestrategie aminoacylierter Dimerfragmente der tRNA mittels Festphasensynthese
… die Dimersynthese wurden N-aryloylgeschützte 5‘-Phosphoramidite des Adenosins und Desoxycytidins synthetisiert. Nach der Dimersynthese wurde dieses orthogonal zur Abspaltung mit konzentriertem Ammoniak entschützt. Aufgrund einer partiellen Abspaltung des Dimers während des Entschützungsschrittes …
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Conjugation of oligonucleotides for drug delivery via a linker derived from Meldrum’s acid and A capture-release method to synthesize long oligonucleotides
… for the synthesis of a propargylated glycerol phosphoramidite as a 5’-end label. Incorporation of this alkyne into oligonucleotides by solid-phase synthesis will enable the capture of the full-length sequences using azido-modified magnetic beads through a Copper-Catalyzed Azide–Alkyne …
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Synthesis of internal amide bond short interfering RNAs (siRNAs) and investigation of their gene silencing properties
… In this thesis, we proposed to utilize phosphoramidite chemistry to localize internal amide-bond modifications [6]. A practical synthesis of a peptide nucleic acid unit combined with an RNA nucleoside (PNA-RNA dimer, UaU) is reported [7]. Using this PNA-RNA dimer phosphoramidite allows …
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Nucleoside and oligonucleotide approaches towards potential HIV chemotherapies
… using either the appropriate aralkyl-substituted phosphoramidite or by post-synthetic substitution of a pentafluorophenoxy substituent by N-methylphenethylamine. The presence of phenethyl or benzoyl substituents invariably resulted in thermodynamic destabilisation of all duplexes studied. The …
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