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Showing 1 to 20 of 140 for “"regioselectivity"”.
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Recombinant production and regioselectivity study of lytic polysaccharide monooxygenases
… understand the determinants of this oxidative regioselectivity. For this, four fungal and two bacterial LPMO representatives were produced in Pichia pastoris and Escherichia coli, respectively. Carefully studying the mixture of products released from cellulose by these enzymes and their …
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Chemical Reactivity and Regioselectivity of Trimetallic Nitride Endohedral Metallofullerenes
… addresses the chemical reactivity and regioselectivity of TNT EMFs. Based on the extraordinarily high stability of TNT EMFs relative to empty cage fullerenes and classic endohedral metallofullerenes, macroscopic quantities of high purity TNT EMFs were obtained directly from crude soot …
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Predicting Flavonoid UGT Regioselectivity with Graphical Residue Models and Machine Learning.
… the prediction of flavonoid UGT acceptor regioselectivity from primary protein sequence. Novel indices characterizing graphical models of protein residues are introduced. The indices are compared with existing amino acid indices and found to cluster residues appropriately. A variety of …
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Probing regioselectivity in the Diels -Alder cycloadditions between *[60]fullerene and aryl substituted acenes
… while electron withdrawing groups reduce 5,12 regioselectivity. Direct evidence for aryl CH-fullerene pi interactions comes from a careful examination of 1H NMR chemical shifts for the ortho phenyl protons in fullerene-acene adducts. A careful review of the Cambridge Crystallographic Database …
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The nickel-catalyzed Mizoroki-Heck reaction : high regioselectivity in Olefin migratory insertion and photoredox-enabled indoline formation
… from iodoacetanilides and alkenes. Very high regioselectivity for 3-substituted indoline products is obtained for both aliphatic and styrenyl olefins. Mechanistic investigations indicate that oxidation to Ni(III) is necessary to perform the difficult C-N bond-forming reductive elimination, …
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An Exploration of Ion Pairing Interactions as a Tool to Control Regioselectivity in Iridium-Catalysed C–H Borylation
… in transition metal catalysis for control of regioselectivity. Specifically, ion pairing was investigated for achieving meta and para selectivity in iridium catalysed C–H borylation. An ion pairing interaction between a functionalised ligand and matching functionality on a substrate was …
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Total synthesis of (±)-cis-trikentrin B, (±)-herbindole A and (±)-herbindole B. investigation into the regioselectivity of 6,7-Indole aryne cycloadditions
… the effect of 3- and 4-substitution on the regioselectivity of 6,7-indole aryne cycloadditions with 2-tertbutylfuran. The results of this investigation disclose that substitution at the 3-position on the indole ring in particular results in remarkable regiocontrol that favored the …
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Selective, nickel-catalyzed carbon-carbon bond-forming reactions of alkynes
… types of substituted olefins. Controlling both regioselectivity and (EIZ)- selectivity in such transformations presents a significant challenge. In reactions that also involve the creation of a new stereocenter, the development of enantioselective processes is highly desirable. Several novel, …
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Transition metal-catalyzed olefin functionalization for highly regio-, enantio-, and chemoselective C–X bond formation
… or 1,3-aminothioethers with excellent degrees of regioselectivity is reported. Bidentate phosphine ligands with larger natural bite angles (βn ≥ 99°) promote a Markovnikov-selective hydrothiolation in up to 88% yield and >20:1 regioselectivity. Conversely, when smaller bite angle ligands (βn ≤ …
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Mutagenic studies into the catalytic versatility of soluble methane monooxygenase
… aromatic substrates. All mutants showed relaxed regioselectivity with all substrates assayed. However no evidence of a gating residue was found, indicating that Leu110 is more important in determining regioselectivity than substrate access to the active site. Comparison to the highly similar …
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Nickel-catalyzed intermolecular reductive couplings of alkynes and aldehydes ; Enantioselective synthesis of (-)-terpestacin and structural revision of siccanol using catalytic stereoselective fragment couplings and macrocyclizations
… allylic alcohols with high stereoselectivity and regioselectivity. In most cases, a 1:1 ratio of alkyne to aldehyde was sufficient for efficient coupling. The yield and regioselectivity were strongly dependent on the phosphine ligand, but the allylic alcohols formed were invariably the products of …
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Recent Advances in Indole Aryne Cycloaddition Chemistry. Part I: Total Synthesis of (±)-cis-Trikentrin B. Part II: Investigation into the Regioselectivity of 6,7-Indole Aryne Cycloadditions. Part III: Synthesis and Reactions of Novel Tribromoindoles
… effect of 2-, 3-, 4- and 5-substitution on the regioselectivity of 6,7-indole aryne cycloadditions with 2-tert-butylfuran. The results of this investigation indicated that the degree of polarization of the 6,7-indole aryne bond depends on electronic nature and the positions of the various …
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Development of new transition metal-catalyzed carbon-fluorine, carbon-nitrogen, and carbon-carbon bond forming processes
… due to the trans-effect, caused the poor regioselectivity of the fluorination reaction under TESCF₃-free conditions. An in situ ligand modification by trifluoromethyl anion, leading to the generation of the cis-LPd(vinyl)F complex which prefers reductive elimination rather than Phydrogen …
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Nickel-catalyzed reductive coupling reactions of 1,6-enynes and the total synthesis of (+)-acutiphycin
… nickel species as a plausible explanation of regioselectivity in the nickel-catalyzed reductive coupling of aldehydes and 1,6-enynes. In the absence of a phosphine additive, high regioselectivity and high diastereoselectivity are obtained as a direct result of coordination of both the alkyne …
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The Application of Catalysis based on Hydrogen Bonding and Ion-pairing Interactions to Asymmetric Minisci-type Alkylations of Azines and Iridium-Catalysed C-H Borylation.
… of how such approaches can be applied to regioselectivity and enantioselectivity challenges in synthetic chemistry. The most widely used interactions, hydrogen bonding and ion-pairing, are employed in this thesis for the accomplishment of two important transformations in an …
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Synthesis of indoles via palladium-catalyzed annulation of aryl chlorides and internal alkynes
… in good to excellent yield with a high level of regioselectivity in most cases. Alkynes with alkyl, aryl, alkenyl, and trialkylsilyl substituents are compatible with this methodology.
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Dirhodium(II,II) paddlewheel complexes conjugated to a polypyridyl tris-amine scaffold: synthesis and application as asdjncaslpre-catalysts in the hydroformylation of 1-octene
… toward aldehydes (>98%) with moderate regioselectivity towards linear products (40-44%). Excellent conversion (97-99%), moderate to good chemoselectivity toward aldehyde products (59-87%) and moderate to good regioselectivity (48-71%) where obtained for diphenylformamidine compounds. …
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