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Showing 1 to 15 of 15 for “"lactonization"”.
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I Progress towards the synthesis of plakortether B through a zinc-mediated homologation II Synthesis of novel hydroxy-cyclopropyl peptides isosteres
… of homologation-cyclopropanation-rearrangement-lactonization reactions. Amino acid-derived beta-keto imides were synthesized in order to enhance the stereocontrol of the tandem lactonization reaction. The use of amino acid derived beta-keto imides was beneficial in two ways; first it …
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The synthesis and evaluation of valine mimic protio and halo enol lactones as human neutrophil elastase inhibitors
… an overall yield of 40%. Protio enol lactonizations were performed with mercury(II) catalysis in CH$\sb2$Cl$\sb2$ or CH$\sb2$Cl$\sb2$-H$\sb2$O. Stereoselective Z-bromo enol lactonization was carried out by Br$\sp+$-induced lactonization in the presence of Ag$\sp+$. E-Bromo enol …
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Cyclization modes in type III polyketide synthases and the synthetic compounds used as probes for mechanistic studies.
… 32a was also synthesized in order to probe the lactonization mechanism in type III PKSs such as PpASCL and AthPKSA. It has been suggested that diketo acids are synthesized by these enzymes, released, and then lactonized in solution. The results of this study show that even prolonged incubation …
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Rapid Synthesis, Characterization, and Catalytic Function of Rhodium(III) and Iridium(III) Chloro-bridged Dimers
… and examined as catalysts for oxidative lactonization of 1,4- and 1,5-diols. Oxidative lactonization of 1,4-butanediol to afford γ-butyrolactone proceeded selectively and efficiently using [(η5-Me4C5R)IrCl]2(μ2-Cl)2 as the catalyst. Several R substituents were tested to assess electronic …
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Synthetic Routes to Therapeutic Agents Via Masked Functionalities: From Orthogonal Peptide Crosslink to Photothermal Cancer Prodrug
… 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 systems on the release of …
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Design and Synthesis of Enzyme Activated Irreversible Inactivators for Proteases. Suicide Inactivation of Chymotrypsin
… been investigated. The catalytic mercury induced lactonization of acetylenic acids has been studied, and shown to proceed via a mercuronium intermediate, to give enol lactones in good yield. This methodology was adapted to afford halo-enol lactones in modest yields, and a direct halolactonization …
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Synthesis and Antiviral Evaluation of Some 3'-Carboxymethyl-3'-deoxyadenosine Derivatives
… and an efficient new method for lactonization of 2'-O-TBDMS-3'-deoxy-3'-[(ethoxycarbonyl)methyl]adenosines to give corresponding 2', 3'-lactones was also developed. Target compounds were evaluated for anti-HIV and anti-HIV integrase activities, but were not active at the …
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Towards the Total Synthesis of Antascomicin B. Efforts to Construct the C1-C21 Fragment
… found a surprisingly high yielding acid mediated lactonization that was employed to cleave the α-methylbenzyl amide. Details of these studies and further elaboration of the lactone are discussed. We also describe the progress toward the synthesis of the C1-21 fragment of the natural product.</p>
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Copper-Catalyzed Amino Oxygenation of Alkenes and Dienes: A Novel Amino-Initiation Pathway Using O-Benzoylhydroxylamines
… and oxidant. First, copper-catalyzed amino lactonization was achieved starting with carboxylic acid-tethered alkenes. This intramolecular transformation is also applicable to alcohols, amides, 1,3-diones, oximes, and thioic acids as nucleophilic trapping partners. These reactions proceed in …
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Mechanisms of Enzyme Neofunctionalization in Plant Specialized Metabolism
… (COSY) that catalyzes the isomerization and lactonization in coumarin biosynthesis. This study unveils the emergence of an unconventional catalytic mechanism mediated by a BAHD-family enzyme, and sheds light on its recruitment to the evolutionarily new coumarin biosynthetic pathway in …
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Synthetic Studies on Small Molecule Modulators of Src Homology 2 (SH2) Domain-Containing Inositol 5’-Phosphatase (SHIP)
… utilizing an allylic oxidation, ozonolysis, and lactonization for a more selective and controlled synthesis. In addition, this work has led to the synthesis of several new AQX-1125 analogs, providing information on structure activity relationships in this structural class of SHIP1 agonists.</p>
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Production of Bio-based Lactone Monomers for Intrinsically Recyclable Plastics
… catalyze our probe reaction of methyl lactate lactonization to lactide. From these computations, we identified titanium-containing zeolite with the MEL topology as a promising catalyst for this reaction in the gas phase. Continuous-flow kinetic studies revealed that Ti-MEL showed 40% increased …
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Rhodium-Catalyzed Enantioselective Desymmetrizations of Oxabicyclic Alkenes and Alkene Difunctionalization via Nickel-Catalyzed Arylcyanation
… in that one diastereomer was capable of lactonization and the other was not. This led to the enantioselective synthesis of chiral oxazinones, which are similar to the naphthoxazine class of compounds which possess dopaminergic activity.
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Synthesis of a triglyceride containing a lactonizable hydroxy fatty acid and investigations into the behavior of this triglyceride and related lactones with application to the analysis of beef tallow
… was then derivatized to prevent spontaneous lactonization of hydroxy fatty acids. A number of methods were evaluated for the preparation of the methyl ether, trimethylsilyl and t-butyldimethylsilyl derivatives of the hydroxy function. Only the trimethylsilyl derivative proved successful due …
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Synthesis and function of the conserved motif of mycosamine-containing polyene macrolides
… of a new type of diastereotopic group-selective lactonization and a new directing group for the challenging installation of the mycosamine sugar. This building block may help enable the modular synthesis of these natural products and their derivatives not readily accessible via degradation. …