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Showing 1 to 20 of 36 for “"regiospecific"”.
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Regiospecific Synthesis of Ortho Substituted Phenols
… ring which could be a major concern in the regiospecific synthesis of phenols. AES and Directed <em>ortho</em>--Metalation (DoM) are the only ways to directly substitute a proton on an aromatic ring and to synthesize regiospecifically substituted phenols. Phenol is a versatile precursor to a …
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Studies in regiospecific oxidation reactions of 1-methyl-pentacyclo[5.4.0.02,6.03,10.05,9]undecane-8,11-dione.
Baeyer-Villiger oxidation of 1-methylpentacyclo[5.4.0.02,6.03,10.05,9] undecane-8,11-dione, performed by using m-chloroperbenzoic acid in 1:1 molar ratio, resulted in the formation of monolactone. The corresponding dilactone, was synthesized by reacting 1-methyl-PCU-8,11-dione with …
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Part I. Aromatic Fluorinations for Fluorine-18 Labeling of Estrogens. Part Ii. Bromodesilylation-Potential Method for Regiospecific Radiobromination of Aromatic Systems. Part Iii. Synthesis of Isohexestrol and Isohexestrol Derivatives
Two aromatic fluorination methods, the decomposition of aryl azides and the decomposition of aryl triazenes, were investigated as methods potentially suitable for fluorine-18 labeling of estrogens. The aryl triazene method gives moderate yields in many systems, but fails with ortho methoxy or …
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Directed Ortho-Metalation of the Three Methyl Anisoles in Various Media
… of substituted aromatic compounds. DoM is highly regiospecific providing metalation chiefly in the ortho-position. However, lateral (a-) metalation of an alkyl side-chain and ortho-metalation of a second ortho-position can compete. Investigation of the three methylanisoles was therefore undertaken …
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The total synthsis off linear anthrasteroids.
… Hajos and D.R. Parrish. This intermediate was regiospecifically annulated to give the novel tricyclic enone, (+/-)-1beta-t-butoxy-9abeta-methyl-l,2,3,3aalpha,4,7,8,8abeta,9,9a-decahydro-6-benz[f]indenone via two different routes. Thestereochemistry of the new ring junction was elucidated by …
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Formation of 2-halomethylene-4-cyclopentene-1,3-diones and/or 2-halo-1,4-benzoquinones, total synthesis of methyl linderone and Wacker-type oxidation of aryl-substituted alkenes
… of facile, palladium catalyzed, direct, and regiospecific Wacker-type oxidations has been developed to yield various alpha-arylated ketones from aryl-substituted internal alkenes.
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Synthesis of naphtho{2,3-c}pyrans including the aphin-derived quinone A'
… of a trifluoroethylnaphtho-1, 4-quinone via a regiospecific trifluoroacetylation of an appropriately substituted naphthalene. Chapter Two describes the synthesis of the methyl ethers of the naturally occurring quinones A and deoxyquinone A for evaluation of their "anti-cancer" activity by the …
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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
… Citrus sinensis and Perilla frutescens effected regiospecific deprotonation, but pinene cyclases I and II from Salvia officinalis deprotonate non-regiospecifically. Deuterium isotope effects on the monoterpene product distribution from incubations of (1-$\sp3$H;8,9-$\sp2$H$\sb6$) GPP with the …
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Reinventing Aromatic Substitution: A Novel Look
… affords only modest yields and does not provide regiospecific substitution of most substituted aromatics because most contain <em>ortho</em>/<em>para</em> directors which afford mixtures of isomers. The novelty of our procedure for the synthesis of the iodinated aromatics is twofold in that …
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Phosphorus-Stabilized, Carbanion-Accelerated Claisen Rearrangements: Asymmetric Induction via 1,3,2-Oxazaphosphorinanes
… in high yield, and the rearrangements are regiospecific and highly stereoselective. Most importantly, the first examples of asymmetric induction in the Claisen rearrangement with chiral phosphorus anion-stabilizing groups are documented. The observed asymmetric induction, which is highly …
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Combinatorial gene regulation by transcription factors
… of TF function and generate new hypotheses about regiospecific binding patterns and functions of TF classes within enhancers.
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Directed Ortho-Metalation of Dimethylarylamines
… by organolithium reagents which provides regiospecific substitution exclusively at the ortho- position (equation). The focus of this study is to find hydrocarbon media that will permit the maximum extent of metalation of several dimethylarylamines. The dimethylamine-containing substituents …
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Structure Determination of Natural Product Biosynthesis Enzymes
… on the molecular mechanisms governing intricate regiospecific and stereospecific modifications laying the foundation for future bioengineering and synthetic biology initiatives. This thesis work describes the CalS10, DynU16 and AtmM structures determined by X-ray crystallography and kinetic …
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Novel quinone syntheses
… In Chapter II we have sought to develop, via regiospecific Diels-Alder additions, simple syntheses of some synthetically useful napthaquinonoid systems. The formation of many of these, required in the past as intermediates for the syntheses of a number of naturally occurring quinones, has …
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Synthesis of Limonoid and Steroidal intermediates
… to a bicyclic enone 104 in eight steps. Regiospecific alkylation followed by medium pressure hydrogenation and epimerization yielded the hydrindane 110. Extensive NMR analysis of this compound was used to provide conclusive evidence of 110's absolute stereochemistry. This route is …
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Structural analysis of hydroxypropylphosphonic acid epoxidase : a fosfomycin biosynthetic enzyme
… the R-HPP substrate suggest a mechanism for the regiospecific reactions catalyzed by the enzyme. This regiospecificity of HppE catalysis is also observed when substrates R- and S-2-phenylethlylphosphonic acid (HPEP) are used, where a methyl group has been substituted by a larger phenyl …
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A Convenient Synthesis of Pyrrolnitrin and Related Halogenated Phenylpyrroles
… the cross-coupling partners, we report a regiospecific and high yielding synthesis of a 3-chloro pyrrole compound 2.14, its brominated analog 2.16, an iodinated analog 2.17, and the corresponding pinacolboronate ester 2.18. We also report a generalized reaction sequence …
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Synthesis of Single Isomer Trisubstituted Olefins from beta-chloro-alpha-iodo-alpha, beta-Unsaturated Esters and Alkynyl Esters
A convenient method to synthesize regiospecific and stereoselective trisubstituted olefins bearing three substitutents with various functionalities is disclosed. A unique olefin template such as (E)-beta-chloro-alpha-iodo-alpha,beta-unsaturated esters cross-couple with 9-alkyl-9-BBN to produce …
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Strategies towards the synthesis of prostaglandin analogues
… followed by base-mediated methodology to affect regiospecific enolate generation. Effective trapping of the enolate generates the requisite target. Within the context of this strategy both 2- and 3-component coupling protocols have been elaborated. Having demonstrated that the a- and p- …
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Synthesis and characterization of triphenylphosphine oxide containing monomers and high performance polymeric materials
… chloride is a viable method for preparing regiospecific triphenylphosphine oxide derivatives. These derivatives were oxidized, nitrated and reduced to afford isomeric triphenylphosphine oxide containing diamines. Moreover, a sequential addition procedure with thiophosphoryl chloride, …
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