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Showing 1 to 20 of 208 for “"nucleophiles"”.
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New applications of heteroarylzinc nucleophiles
… and other aryl and heteroaryl organometallic nucleophiles. Aiming for a practical and effective alternative to 2-pyridylboron reagents, a solid 2-pyridylzinc compound was prepared and is described in Chapter 1. Chapter 2 details a new approach to the synthesis of sulfonamides using aryl and …
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Reaction of Nucleophiles With Perfluoroalkyl, Perfluoroacyl and Perfluoroalkanesulfonyl Groups
Trifluoroacetyl triflate is readily prepared in 82% yield by the dehydration (phosphorus pentoxide) of a 2:1 mixture of trifluoroacetic acid and trifluoromethanesulfonic (triflic) acid. Reactions of this highly electrophilic trifluoroacetylating reagent with alcohols, ketones, ethers, amines, …
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A study of various nucleophiles in aromatic SRN1 reactions
Various nucleophiles were subjected to SRNl (nucleophilic substitution via a radical chain mechanism) conditions with representative carboaromatic and heteroaromatic substrates. Upon 5-25 min of near-UV irradiation, the carbanions of 2-benzyl-4,4-dimethyl-2-oxazoline, ethyl phenylacetate, t-butyl …
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The effects of solvents and nucleophiles on heteroaromatic SRN1 reactions
… and acetonitrile anions were employed as nucleophiles for heteroaromatic SRN1 reactions. The photostimulated reaction of 2-chloroquinoline with potassioacetonitrile in liquid ammonia was complicated by 11 polymer 11 formation and by SNAR2 and SN(ANRORC) reactions with equilibrium …
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Nickel-catalyzed cross-coupling reactions involving secondary and tertiary alkyl nucleophiles
… some reports have demonstrated the use of C(sp3) nucleophiles and electrophiles in cross-coupling reactions. However, use of secondary and tertiary alkyl nucleophiles has remained a challenge due to competitive β-hydride elimination and slow transmetallation of bulky secondary and tertiary alkyl …
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Deoxyribozymes for peptide substrates: exploring the landscape of nucleophiles and electrophiles
… that catalyze reactions involving amine nucleophiles. We also sought to identify deoxyribozymes that can covalently tag phosphopeptides with RNA. These studies are described in Chapter 5. Such deoxyribozymes can be employed as reagents to isolate phosphopeptides from a mixture of …
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Reactions of 4-chloro-2,6-dimethoxypyrimidine and 2-chlorothiazole with carbanion nucleophiles
Reactions of 4-chloro-2,6-dimethoxypyrimidine (1) with enolates of acetone, pinacolone, diisopropyl ketone, and ethyl phenylacetate generated by means of potassium amide in 1 liquid ammonia were found to proceed by the S<sub>RN>1 mechanism upon photostimulation with near-UV light to give good …
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Reactions of various aromatic nitro-compounds and anthraquinones with selected bases and nucleophiles
The Introducti on deals mainly with hi storical studies on aryne chemi stry and ring closure via arynes , hydride replacement from aromatic rings by nucleophi les, c l eavage of anthr aquinones in basic medium and the Leuckart reaction . This work can be divided into two main s ect i ons. Section I …
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The selective palladium-catalysed decarboxylative coupling of nucleophiles in the presence of propargylic electrophiles
… of 1,3-dicarbonyl compounds and nitrogen nucleophiles in the presence of propargylic electrophiles. The first part of this thesis focuses on the palladium-catalysed cross-coupling reaction involving two 1,3-dicarbonyl compounds in a regio- and chemoselective manner via an allylic linker. …
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Construction and Application of Reference Scales for the Characterization of Cationic Electrophiles and Neutral Nucleophiles
… electrophiles (benzhydrylium ions) and reference nucleophiles (pi-systems) has been constructed on the basis of the equation log k = s(E+N), which covers reactivity ranges of several orders of magnitude. The reference compounds of this basis-set proved to be very useful for the determination of …
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Scope and stereochemistry of carbon-carbon bond formation via addition of carbon nucleophiles to nitrones
… acetate. However, similar additions of carbon nucleophiles to 4-t-butyl-2,3,4,5-tetrahydropyridine N-oxide afforded only the trans isomer from axial addition in moderate yields (60-68%). The stereoselectivity in these endocyclic nitrone additions can be explained by a stereoelectronic effect …
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A Study of the Interaction of some cationic Transition-Metal compounds with Carbon Monoxide and Nucleophiles
… The work also investigates the attack of nucleophiles on such species and examines the feasibility of these reactions as a possible first step in the catalytic production of organic esters. Mono and dipositive species of ruthenium have been effectively prepared by the reaction of [RuCl 2 …
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Gold(I) and Platinum(II)-Catalyzed Hydrofunctionalization of Allenes and Alkenes with Carbon and Nitrogen Nucleophiles
… However, a nucleophile screen failed to identify nucleophiles other than cyclic ureas and 2-oxazolidinone that efficiently undergo hydroamination with 1-alkenes. Various carbamates, arylamines, amide derivatives, sulfur-containing amide derivatives, and α-heteroatom compounds failed to react …
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Tertiary N-acyl phosphoramidates : a mechanistic study of their formation and collapse in reactions with nucleophiles
Different synthetic approaches to tertiary mixed phosphoric-carboxylic imides(III) are discussed. The preparation of (III) via the N-acylation of phosphoramidates was investigated. The reaction of PhC(O)X (X = Br, Cl, F) with the conjugate base of (EtO)₂P(O)NHMe (IX) yields three products: PhCO₂Et …
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The elucidation of single electron transfer (SET) mechanisms in the reactions of nucleophiles with carbonyl compounds
… ring opening. In reactions between <b>20</b> and nucleophiles known to react via SET with carbonyl compounds, 20 successfully produced products characteristic of SET pathways. However, subsequent studies of the reaction between <b>20</b> and thiophenoxide, a nucleophile purported to undergo SET, …
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Ring-Opening of Aziridine -2 -Carboxamides by Carbohydrate C1-O Nucleophiles. Stereoselective Preparation of O-Linked Glycopeptides
A new method for the synthesis of O-linked glycopeptides is described. The method uses the carbohydrate C1-O nucleophilic ring-opening of aziridine-2-carboxamides to access the target O-linked glycopeptides. The synthesis of the alpha-GalNAc-Ser class of glycopeptides is emphasized and either the …
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Photolysis of fluorinated organic molecules: fluorine mass balances and the roles of nucleophiles, rings, and degree of fluorination
Organofluorine containing pharmaceuticals and pesticides are widely used resulting in their accumulation within the environment. When these chemicals are exposed to environmental conditions, abiotic degradation pathways such as photolysis may occur. Photolysis results from photon absorption by a …
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Studies in Asymmetric Catalysis: Lewis Base catalyzed/Lewis Acid Mediated Aldol Reactions of Ketone- and Amide Derived Nucleophiles
Additionally, the use of the silicon tetrachloride---chiral phosphoramide system has proven a competent catalyst for highly selective vinylogous aldol reactions between dienolates derived from a variety of alpha,beta-unsaturated carbonyl compounds to aldehydes. These reactions provided high levels …
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Synthesis of Cyclopropane-Fused 1,5-Diazocin-2-ones via Metal-Templated Intramolecular Addition of Nitrogen Nucleophiles to Pre-Generated Cyclopropenes
… intramolecular nucleophilic addition of nitrogen nucleophiles to the cyclopropene double bond in a direct 8-membered cyclization. This method allows for access to previously-unknown diazocines of their type – namely, 1,5-diazocin-2-ones possessing fusion to a cyclopropane moiety. The described …
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Applications of planar-chiral phosphaferrocene-oxazolines in asymmetric catalysis and enantioselective desymmetrization by carbon nucleophiles in the presence of chiral ligands
… of cyclic anhydrides and imides by carbon nucleophiles is described. By employing a Grignard reagent/chiral ligand complex as the nucleophile, a range of anhydrides and imides are effectively desymmetrized with uniformly high enantiomeric excess. In these reactions, (-)- sparteine is shown …
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