Edit Y. Tshuva

Bio: Edit Y. Tshuva is an academic researcher from Hebrew University of Jerusalem. The author has contributed to research in topics: Ligand & Polymerization. The author has an hindex of 31, co-authored 93 publications receiving 3687 citations. Previous affiliations of Edit Y. Tshuva include Bar-Ilan University & Tel Aviv University.

Synthetic models for non-heme carboxylate-bridged diiron metalloproteins: strategies and tactics.

Abstract: Metalloproteins perform a variety of functions in biological systems. The catalysis of several remarkable chemical transformations occurs at metal centers embedded in the active sites of metalloenzymes. Metalloproteins having carboxylate-bridged diiron cores comprise an important class, with functional versatility despite obvious structural similarities.1-7 The functions performed by these proteins and their significance have inspired a range of biomimetic studies, which in turn suggest possible chemical, biological, and pharmaceutical applications.1,8-11 The development of small molecule synthetic model compounds for non-heme dinuclear iron-based metalloproteins is a challenging field. In this article we review two decades of progress in the area. Table 1 lists metalloproteins that have now been identified to share the carboxylate-bridged diiron active site motif.3,4,6,7 Their various roles in nature are delineated. Some have been thoroughly investigated, and their X-ray structures are available. Examples include hemerythrin,12 methane monooxygenase,13,14 and ribonucleotide reductase.15,16 Others are assigned to the carboxylate-bridged diiron family according to gene sequence analysis and, occasionally, available spectroscopic data. The first carboxylate-bridged diiron protein to be discovered was hemerythrin (Hr), which has been studied since the 1950s.12 Hemerythrins are dioxygen carrier proteins found in marine invertebrates. They are functional analogues of the mammalian proteins myoglobin and hemoglobin. The active site of hemerythrin (Scheme 1) is composed of two iron atoms bridged by two carboxylate ligands from glutamate and aspartate residues. Five terminally bound histidine units and a bridging hydroxo group complete the coordination spheres of the two iron atoms, one of which is six-coordinate and the other five-coordinate in the reduced, diiron(II) state of deoxy Hr. Upon reaction with O2, deoxy Hr is converted to oxy Hr, in which an η1-hydroperoxo group binds to the available coordination site and forms a hydrogen bond to the bridging oxo unit. Biomimetic studies of this protein have advanced the understanding of the mechanism * To whom correspondence should be addressed. E-mail: lippard@ lippard.mit.edu. 987 Chem. Rev. 2004, 104, 987−1012

Isospecific Living Polymerization of 1-Hexene by a Readily Available Nonmetallocene C2-Symmetrical Zirconium Catalyst

Abstract: The search for newR-olefin polymerization catalysts based on transition metal complexes is a field of major interest involving many academic and industrial research groups. The ligands surrounding the metal play a crucial role in determining the activity as well as the stereospecifity of the catalyst, by affecting the steric and electronic properties at the metal. Over the last two decades, this field has been dominated by the metallocene complexes of group IV metals. Especially, ansa-metallocenes of C2 symmetry were found to induce isospecificity in the resulting polymers. 1 Recently, there has been a growing interest in the development ofnon-cyclopentadienyl ligands for the polymerization of R-olefins.2 Most attention was drawn to chelating di(amido) ligands, 3 some of whose group IV transition metal complexes induce polymerization in a liVing manner, 3a-c whereas chelating di(alkoxo) ligands 4 drew a more limited attention. The number of nonmetallocene systems, which were found to induce tacticity in the resulting polymer, is, however, quite small. 5 In this communication we introduce a novel family of di(alkoxo) complexes, one member of which is the first nonmetallocene C2symmetrical complex, which, upon activation, leads to a highly isospecific living polymerization of 1-hexene. Recently, we introduced the amine bis(phenolate) family of ligands to group IV transition metals. 6 We found that the presence of an extra donor group on a sidearm leads to octahedral LigMX 2type complexes, in which the two labile X groups are forced into a cis geometry. 6a Catalysts derived from these complexes (e.g. 1a) lead to highly reactive 1-hexene polymerization catalysts. 6b The Cs-symmetry of1a allows olefin approach from the two possible directions in each active position without preference, thus the polymer obtained is atactic. Therefore, we aimed at complexes of a different symmetry which may induce tactic polymerization, that incorporate ligands having similar functional groups yet having a different connectivity. Our approach is based on replacing the “branched” mode of connectivity of donor atoms with a sequential connectivity mode, namely diamine bis(phenolate) ligands. This new family of dianionic tetradentate chelating ligands is easily synthesized by a one-pot Mannich condensation between readily available di(secondary) amines, formaldehyde, and substituted phenols as demonstrated in eq 2. 2, a structural isomer

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

Advances in non-metallocene olefin polymerization catalysis.

Abstract: B. Anionic Ligands 302 IX. Group 9 Catalysts 302 X. Group 10 Catalysts 303 A. Neutral Ligands 303 1. R-Diimine and Related Ligands 303 2. Other Neutral Nitrogen-Based Ligands 304 3. Chelating Phosphorus-Based Ligands 304 B. Monoanionic Ligands 305 1. [PO] Chelates 305 2. [NO] Chelates 306 3. Other Monoanionic Ligands 306 4. Carbon-Based Ligands 306 XI. Group 11 Catalysts 307 XII. Group 12 Catalysts 307 XIII. Group 13 Catalysts 307 XIV. Summary and Outlook 308 XV. Glossary 308 XVI. References 308

Iron-Catalyzed Reactions in Organic Synthesis

Abstract: A new iron(III) halide-promoted aza-Prins cyclization between γ,δ-unsaturated tosylamines and aldehydes provides six-membered azacycles in good to excellent yields. The process is based on the consecutive generation of γ-unsaturated-iminium ion and further nucleophilic attack by the unsaturated carbon−carbon bond. Homoallyl tosylamine leads to trans-2-alkyl-4-halo-1-tosylpiperidine as the major isomer. In addition, the alkyne aza-Prins cyclization between homopropargyl tosylamine and aldehydes gives 2-alkyl-4-halo-1-tosyl-1,2,5,6-tetrahydropyridines as the only cyclic products. The piperidine ring is widely distributed throughout Nature, e.g., in alkaloids,1 and is an important scaffold for drug discovery, being the core of many pharmaceutically significant compounds.2,3 The syntheses of these type of compounds have been extensively studied in the development of new drugs containing six-membered-ring heterocycles.4 Reactions between N-acyliminium ions and nucleophiles, also described as amidoalkylation or Mannich-type condensations, have been frequently used to introduce substituents at the R-carbon of an amine.5 There are several examples that involve an intramolecular attack of a nucleophilic olefin into an iminium cation for the construction of a heterocyclic ring system.6 Traditionally, the use of hemiaminals or their derivatives as precursors of N-acyliminium intermediates has been a common two-step strategy in these reactions.6a Among this type of cyclization is the aza-Prins cyclization,7 which uses alkenes as intramolecular nucleophile. However, cy† X-ray analysis. E-mail address: malopez@ull.es. (1) (a) Fodor, G. B.; Colasanti, B. Alkaloids: Chemical and Biological PerspectiVes; Pelletier, S. W., Ed.; Wiley: New York, 1985; Vol. 23, pp 1-90. (b) Baliah, V.; Jeyarama, R.; Chandrasekaran, L. Chem. ReV. 1983, 83, 379-423. (2) Watson, P. S.; Jiang, B.; Scott, B. Org. Lett. 2000, 2, 3679-3681. (3) Horton, D. A.; Bourne, G. T.; Smythe, M. L. Chem. ReV. 2003, 103, 893-930. (4) Buffat, M. G. P. Tetrahedron 2004, 60, 1701-1729 and references therein. (5) Speckamp, W. N.; Moolenaar, M. J. Tetrahedron 2000, 56, 3187- 3856 and references therein. (6) (a) Hiemstra, H.; Speckamp, W. N. In ComprehensiVe Organic Synthesis; Trost, B. M., Fleming, O., Heathcock, C. H., Eds.; Pergamon: New York, 1991; Vol. 2, pp 1047-1081. (b) Speckamp, W. N.; Hiemstra, H. Tetrahedron 1985, 41, 4367-4416. (7) (a) Dobbs, A. P.; Guesne, S. J. J.; Hursthouse, M. B.; Coles, S. J. Synlett 2003, 11, 1740-1742. (b) Dobbs, A. P.; Guesne, S. J. J.; Martinove, S.; Coles, S. J.; Hursthouse, M. B. J. Org. Chem. 2003, 68, 7880-7883. (c) Hanessian, S.; Tremblay, M.; Petersen, F. W. J. Am. Chem. Soc. 2004, 126, 6064-6071 and references therein. (d) Dobbs, A. P.; Guesne, S. J. Synlett 2005, 13, 2101-2103. ORGANIC