5,938 research outputs found
Mechanistic Investigations into the Palladium-Catalyzed Decarboxylative Allylic Alkylation of Ketone Enolates Using the PHOX Ligand Architecture
No full textPalladium-catalyzed asymmetric allylic alkylation has become a large and important field for chemical synthesis. Many methodologies in this field offer mild conditions under which challenging and important molecular features can be reliably synthesized, including chiral all-carbon quaternary stereocenters. As a result, palladium- catalyzed asymmetric allylic alkylation has found significant use in total synthesis, and growing use in industry. While the general process of palladium-catalyzed asymmetric allylic alkylation has been studied for decades, there have been a number of recent modifications and developments, such as asymmetric versions of decarboxylative allylic alkylation procedures that are not yet well understood. The development of future implementations and improvements to palladium-catalyzed asymmetric allylic alkylation and related methodologies is expected to be facilitated by a better understanding of these more recent developments, and thus further mechanistic investigation is warranted.
Reported herein is a set of investigations into the palladium-catalyzed decarboxylative asymmetric allylic alkylation of ketone enolates using the PHOX ligand architecture. By monitoring the reaction via 31P NMR, a series of previously unidentified key intermediates is discovered. Two representatives of these key intermediates are isolated and characterized. The solution behavior of these species under reaction-like conditions is studied along with a few novel and related complexes. The role of these intermediates and their impact on the behavior of the reaction and product formation is discussed. Previously confounding experimentally observed behavior for this methodology is rationalized via the properties elucidated for these discovered intermediates.</p
Donald Frederick Haynes Family
No full textDonald Frederick Haynes stands with his wife Lilah Mae (Baer) and daughter Dona Louise. Pastor D. F. Haynes sang in a quartet at the 1946 General Conference Session praise service on the morning of June 14. Donald was the son of evangelist and author Carlyle Boynton Haynes.https://scholarsrepository.llu.edu/general-conference-1946-gallery/1011/thumbnail.jp
Low energy inner valence ionization of the rare gases
No full textMatthew A. Haynes, Birgit Lohmann, D. A. Biava, R. P. McEachran, C. T. Whelan, and D. H. Madiso
Frobenius transfers and p-local finite groups
No full textThesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mathematics, 2004.Includes bibliographical references (p. 43-44).In this thesis we explore the possibility of defining the p-local finite groups of Broto, Levi and Oliver in terms of their classifying spaces. More precisely, we consider the question posed by Haynes Miller, whether an equivalent theory can be recovered by studying maps f: BS --> X from the classifying space of a finite p-group S to a p-complete space X equipped with a stable retract t satisfying a form of Frobenius reciprocity. In the case where S is elementary abelian, we answer this question in the affirmative, by showing that under some finiteness conditions such a triple (f, t, X) does indeed induce a p-local finite group over S. We also discuss the converse in some detail for general S.by KaÅi Ragnarsson.Ph.D
Facile Preparation of N-Glycosylated 10-Piperazinyl Artemisinin Derivatives and Evaluation of Their Antimalarial and Cytotoxic Activities
No full textAccording to the precepts that C-10 amino-artemisinins display optimum biological
activities for the artemisinin drug class, and that attachment of a sugar enhances specificity of drug
delivery, polarity and solubility so as to attenuate toxicity, we assessed the effects of attaching sugars
to N-4 of the dihydroartemisinin (DHA)-piperazine derivative prepared in one step from DHA and
piperazine. N-Glycosylated DHA-piperazine derivatives were obtained according to the Kotchetkov
reaction by heating the DHA-piperazine with the sugar in a polar solvent. Structure of the D-glucose
derivative is secured by X-ray crystallography. The D-galactose, L-rhamnose and D-xylose derivatives
displayed IC50 values of 0.58–0.87 nM against different strains of Plasmodium falciparum (Pf ) and
selectivity indices (SI) >195, on average, with respect to the mouse fibroblast WEHI-164 cell line.
These activities are higher than those of the amino-artemisinin, artemisone (IC50 0.9–1.1 nM). Notably,
the D-glucose, D-maltose and D-ribose derivatives were the most active against the myelogenous
leukemia K562 cell line with IC50 values of 0.78–0.87 M and SI > 380 with respect to the human
dermal fibroblasts (HDF). In comparison, artemisone has an IC50 of 0.26 M, and a SI of 88 with
the same cell lines. Overall, the N-glycosylated DHA-piperazine derivatives display antimalarial
activities that are greatly superior to O-glycosides previously obtained from DHA
Erratum: Achieving plane wave accuracy in linear-scaling density functional theory applied to periodic systems: A case study on crystalline silicon (J. Chem. Phys. (2007) 127 (164712) DOI: 10.1063/1.2796168)
No full textIt has been drawn to the authors' attention that our original article did not appropriately attribute a figure that we had reused from our own previous work.</p
Early Roman Thrace : new evidence from Bulgaria /
No full textIncludes bibliographical references and index.Early Roman Thrace / I.P. Haynes -- Greek traditions and Roman taste : continuity and change in Odessos/Odessus (3rd c. B.C.-3rd c. A.D.) / A. Minchev -- Light industry in Roman Thrace : the case of lime production / L.F. Vagalinski -- Thracian pit sanctuaries : continuity in sacred space / K. Hawthorne, V. varbanov and D. Dragoev -- The 'Thracian horsemen' reconsidered / d. Boteva -- Mortuary archaeology in Roman Thrace : the 'Helikon' funerary complex (Debelt Archaeological Reserve) / P. Balabanov -- Production and consumption of bronzework in Roman Thrace / R. Nenova-Merdjanova -- Language and society in Roman Thrace / N. Sharankov
Phenomenology and research in accounting (and related practices): a critical appreciation
No full textIn this chapter, we consider the philosophical and methodological character of phenomenology, delineating various types of phenomenology. We reflect on what it means to do a phenomenological study in accounting (and organization studies more generally), what is the potential of such study, and what has manifested in actual research. We seek to articulate ways forward in terms of the advancing of critical phenomenology for the analysis of accounting (and related practices)
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