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Showing 1 to 20 of 146 for “"Deprotonation"”.
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The role of cysteine 230 and lysine 238 of biotin carboxylase in the deprotonation of biotin and synthesis of bisubstrate analogy inhibitor of carboxyltransferase
… that cysteine 230 does not play a role in the deprotonation of biotin. However, the K238Q mutation resulted in no formation of carboxybiotin, which showed that lysine 238 has a role in the carboxylation reaction. However, the pK value for lysine 238 was 9.4 or higher, suggesting lysine 238 is …
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Synthetic and Mechanistic Studies of Carbamate-Directed Lithiation Reactions: (1) Assymetric Deprotonation of N-Boc Indolines. (2) the Relationship Between Reactivity and Directing Group Orientation
A series of tin-lithium exchange experiments indicate that rotationally restricted $\alpha$-lithio carbamates have increased configurational stability relative to more flexible analogs. An increase in the rate of epimerization of $\alpha$-lithio carbamates in the presence of $N,\ N,\ N\sp\prime ,\ …
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Stereochemistry, isotope effects, and inhibition of terpene biosynthesis: I. Stereospecificity and mechanism of monoterpene cyclases. II. Inhibition by heteroatom analogs of carbocation intermediates
… The stereochemistry of the terminating deprotonation in limonene biosynthesis was elucidated by radiochemical degradation of ($\sp3$H) carvoximes. Limonene cyclases extracted from Citrus sinensis and Perilla frutescens effected regiospecific deprotonation, but pinene cyclases I and II …
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Binding anions using simple neutral molecules
… complexes were observed in the solid state. Deprotonation of the bound protonated oxo-anion was observed with these 2:1 and 3:1 complexes. The basic diindolylurea motif was then extended by the incorporation of further NH bond donor groups from amide, indole and carbazole functionalities. …
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Synthetic investigation of Mn(I) and Re(I) N-heterocyclic carbene complexes
… approach, in which the ylidene obtained from deprotonation of 1,3-bis(2,4,6- trimethylphenyl)imidazolium chloride was added to the metal substrate, proved to be unsuccessful as isolation of the free carbene should rather be performed in an argon filled glove box under extreme inert conditions. …
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Proton Translocation in the Bacteriorhodopsin Photocycle
… The O to BR transition is rate-limited by the deprotonation of the PRC.
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Development of copper based anti-inflammatory drugs: histodine derivatives
… environment. The sequence of protonation/deprotonation of the ligand was studied with 1H NMR spectroscopy. The first deprotonation of glycyl-L-histidine occurred at very acidic environments, and this was the deprotonation of the carboxylate proton. The second deprotonation occurred at one …
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Enantioselective Alpha-Lithiation of N-Boc-N-(p-Methoxyphenyl)allylamines Mediated by (--)-Sparteine
… configurations opposite to that obtained by the deprotonation sequence. The enecarbamates can be hydrolyzed to aldehydes or reduced to amines, and therefore provide facile entry into chiral homoenolate synthetic equivalents and chiral gamma-lithioamine synthetic equivalents.
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New Strategies and Transformations for the alpha-Functionalization of Amines to Access Chiral Amines
… of amines, thereby enabling the alpha-C–H deprotonation accessible under mild reaction conditions for further derivation. Based on this known process mechanism, we first explored the umpolung functionalization of amines through deprotonation of ketimines/aldimines, then a migratory …
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Enantioselective Synthesis of Drug-like Molecules via Axially-Chiral Intermediates
… 1,4-benzodiazepin-2,5-dione derivatives. For the deprotonation/alkylation of O-Bn and O-TBS substituted (S)-methyl lactate derivatives containing achiral oxazolidinones, we hypothesized that a twisted amide enolate featuring a chiral C(O-)-N axis could sufficiently impart stereochemical …
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Design and Syntheses of Potential Drugs Based on GABA(A) Receptor Pharmacophores
… (MOC) strategy. Disappointingly, most of the deprotonation/alkylations failed, due to various reasons. The failure of the reactions of (S)-alanine-derived tetrahydro-1,4-benzodiazepin-3-ones was probably due to either the unexpected side reactions or the steric hindrance of enolate alkylation. …
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Flexible access to an array of enantiomerically-enriched oxabisipidines and their use as chiral ligands in asymmetric synthesis
… the arena of magnesium-mediated asymmetric deprotonation processes was undertaken. Initial investigations focused on the use of the phenyl-substituted bis-secondary oxabispidine, with studies into the formation of both the corresponding magnesium bisamide and lithium amide species. Such …
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The synthesis and properties of selected transition metal-pyrazole complexes and their application towards homogeneous catalysis
… ligands can theoretically be. generated by deprotonation of transition metal complexes containing n -pyrazole ligands. Reaction of such species with other metal complexes containing labile groups, should provide a route to the synthesis of homobimetallic or heterobimetallic complexes …
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Vanadium and chromium complexes supported by sterically demanding ligands : studies relevant to the reduction of dinitrogen to ammonia
… 5 could be converted to 7 by oxidation/deprotonation using [FeCp2]OTf/(Me3Si)2NLi. The anionic nitride "{[HIPTN3N]V=N}-" could not be obtained through deprotonation of 7, removal of the -SiMe3 group from 9, or the reaction of 1 with azides. Addition of potassium graphite to 5 resulted in …
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Kinetics and Mechanism of Syn, Alpha' Lithiation of Tertiary Benzamides
… complexes followed by rate determining deprotonation. Model studies using N,N,N',N'-tetramethylethylenediamine (TMEDA)
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Ab initio molecular dynamics simulations of lanthanide coordination structures in water and in faujasite
… the free energy of faujasite aluminum tetrahedra deprotonation, with and without lanthanum exchanged in faujasite. The presence of lanthanum makes faujasite deprotonation energetically more favorable, thus making faujasite less hydrophilic. The local structure of water confined in faujasite was …
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FTIR Difference Spectroscopy Studies on Membrane Proteins
… well suited to the investigation of protonation/deprotonation reactions of individual side chains within proteins, as well as any changes that might occur in the strength of H-bonds any change in the overall protein structure. The method can be applied in a static manner, revealing differences …
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Extending applications of magnesium amide bases in asymmetric synthesis and a mild and selective N-debenzylation method
… required within this novel base system and the deprotonation can be performed at a more elevated temperature of -40 °C whilst maintaining high selectivity. This efficient desymmetrisation was applied to a range of cyclobutanone substrates and seven novel enol phosphate products were formed in …
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The Chemistry of Cyclopropylarene Radical Cations
… undergo neither cyclopropane ring opening nor deprotonation but nucleophilic addition. Side-chain oxidation products from Ce(IV) oxidation of methylated anthracenes arose from further reaction of nuclear oxidation products under acidic and higher temperature conditions. An analogous (more …
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