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Showing 1 to 20 of 27 for “"Claisen rearrangement"”.
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The Mechanism of The Para Claisen Rearrangement
Made available in DSpace on 2014-12-05T19:35:57Z (GMT). No. of bitstreams: 1 0009091.pdf: 6690048 bytes, checksum: 0f516a898796ed0c1f383e1839166b3f (MD5) Previous issue date: 1954
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Synthesis and Claisen Rearrangement of Alpha-Ethoxyallyl Vinyl Ethers. Evidence for a Dipolar Transition State
… stereoselectivity, scope, and mechanism of the Claisen-Micheal reaction (8 $\rightarrow$ 11) were explored. The products (e.g. 11) of the Claisen-Micheal reaction, which are enol ethers, are protected equivalents of the adducts obtained from the Micheal reaction of $\alpha,\beta$-enals with …
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Synthesis of Lignans Utilising the Acyl-Claisen Rearrangement: Total Syntheses of (+)-Ovafolinin A, B, (–)-Bicubebin A, B and (+)-Bicubebin C
… depending on the nature of the aryl groups. Rearrangement leading to 4,4- diarylbutanals was the most common transformation and these butanals were reduced to give analogues of seco-lignans. Due to their linear, freely rotatable, structure many of these natural secolignans are reported …
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Phosphorus-Stabilized, Carbanion-Accelerated Claisen Rearrangements: Asymmetric Induction via 1,3,2-Oxazaphosphorinanes
The carbanion-accelerated Claisen rearrangement has been extended to include phosphorus carbanion-stabilizing groups. The appropriately substituted allyl vinyl ethers are synthesized by the nucleophilic addition of allyloxides to phosphorus-substituted allenes, which are obtained in one step from …
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Developments in Acyl-Claisen Rearrangements and Application to Synthesis
The acyl-Claisen rearrangement is a powerful [3,3]-sigmatropic rearrangement of an allylic amine and an acyl chloride derived ketene. The α,β-substituted-γ,δ-olefinic amide 32 derived from this rearrangement has been demonstrated to be a powerful scaffold for elaboration via a number of routes. …
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Investigation of metal mediated reactions for natural product synthesis
… thesis, an ether-directed Pd(II)-catalysed aza-Claisen rearrangement reaction that had previously been developed by the Sutherland group was expanded to include more functionalised rearrangement substrates. This methodology has been applied for the synthesis of several natural products including …
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Synthesis of nucleoside analogues.
… synthesis was performed via the use of an aza-Claisen rearrangement on 1,4-anhydro-2-deoxy-5,6-O-isopropylidene-D-arabino-hex-1-enitol employing trichloroacetonitrile. This reaction proceeded to the desired amide in a facile manner, with excellent yield without the need for thermal …
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Towards the Total Synthesis of Antascomicin B. Efforts to Construct the C1-C21 Fragment
… of antascomicin B involves an asymmetric amino-Claisen rearrangement originally developed by Tsunoda et al.35 report the scalability of the preparation and rearrangement of an allylic amide possessing a silyloxy group at the terminal position of the alkene. The Tsunoda-Claisen rearrangement uses …
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Synthetic Routes to Therapeutic Agents Via Masked Functionalities: From Orthogonal Peptide Crosslink to Photothermal Cancer Prodrug
… paclitaxel side-chain fragment via a tandem aryl Claisen rearrangement and lactonization. The prodrug model system was prepared via coupling of the paclitaxel sidechain alcohol to an acid with a pendant substrate for the rearrangement-lactonization. Claisen rearrangement studies in various solvent …
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Viridiofungins and xeniolide F: target oriented synthesis using different rearrangement reactions of a common substrate class
… of xeniolide F. In both cases, sigmatropic rearrangements of α-allyloxy substituted α,β-unsaturated esters are employed: for the viridiofungin ester synthesis a [2,3]-Wittig rearrangement and for the xeniolide F synthesis a catalytic asymmetric Claisen rearrangement CAC. For both …
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Fused and spiro furanones from tetronic acid synthons: Oxa and azacycles featuring the butenolide ring
… 3-Allyl tetronic acids were generated by Claisen rearrangement of 4-O-allyl tetronates under microwave conditions; a subsequent Conia reaction produced the corresponding spiro cyclopropane furan-2,4-diones. Nucleophilic ring opening with diverse alcohols converted the spiro cyclopropane …
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Synthetic studies towards the total synthesis of discorhabdin C
… the first approach is a newly improved aromatic Claisen rearrangement. The key reaction for the second approach is a novel tin-mediated indole synthesis developed in our laboratory.(DIAGRAM, TABLE OR GRAPHIC OMITTED...PLEASE SEE DAI)
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Novel addition reactions of some benzopyrans
… with ethyl formate yielded a rearrangement product, 3-(2-methylprop-l-enyl)chromone. The reaction of 2-cyclopropyl-2-methyl-3- hydroxymethylenechroman-4-one with hydroxylamine yielded 5-(2-hydroxyphenyl)-4-(4-hydroxy-1-methylbut-1-enyl)isoxazole as a major product. These …
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SYNTHESIS OF NATURAL PRODUCT NEPETANUDONE THROUGH THERMALLY FORBIDDEN [4Π+4Π] CYCLOADDITION IN THE PRESENCE OF LIGHT
… Norrish type reactions, photochemical rearrangements, reactions via dienol intermediates, Paterno-Buchi reaction, photodimerization, photo-claisen rearrangement etc [1]. These reactions have been used to either support the biosynthesis of these compounds or they provide an alternate and …
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Studies towards the synthesis of the core of Sarains A, B, & C
… core, and our approach involves a novel rearrangement of a simpler bicyclic aminal system. This thesis describes various attempts to synthesise cis-fused octahydropyrrolo[2,3-b]pyrrole ring systems that bear an endo acetaldehyde-derived substituent in the 3-position. The research into the …
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New approaches for the synthesis of unusual amino acids
The thermal and metal-catalysed aza-Claisen rearrangement of allylic trichlororacetimidates has found widespread application in the synthesis of nitrogen-containing molecules including alkaloids, antibiotics and unnatural amino acids. We have recently investigated the use of this reaction for the …
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Studies on the biosynthesis of the stephacidins and notoamides. Total synthesis of notoamide S and notoamide T. and Progress toward the synthesis of chrysogenamide A
… derivative synthesized through a late stage Claisen rearrangement. The oxidation of notoamide S affords an achiral azadiene that leads to an intramolecular Diels-Alder providing a new product, notoamide T, containing the bicyclo[2.2.2]diazaoctane ring system with the 6-hydroxy-7-prenyl indole …
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Keteneylidenetriphenylphosphorane as a Versatile C-2 Building Block Leading to Tetronic Acids with Potential Herbicidal and anti-HIV Activity
… is investigated as a means to accelerate Claisen rearrangement reactions. The mechanistic pathway of Claisen/abnormal Claisen rearrangements is investigated in detail. Further examples of 3-dispirodihydrofurandiones are provided with a more in-depth study of the reaction mechanism. The …
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