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Valeria Castelletto Dr. Ian W. Hamley Prof. Rohan A. Hule Dr. Darrin Pochan Prof. 《Angewandte Chemie (International ed. in English)》2009,48(13):2317-2320
An addition to the family : The introduction of β‐amino acid residues into a modified amyloid β peptide fragment resulted in well‐defined helical nanoribbons (see cryo‐TEM image) comprising β strands mainly oriented perpendicular to the ribbon axis. The nanoribbons order into a flow‐aligning nematic phase at higher concentration. The β‐strand nanoribbon structure is an addition to the known set of secondary structures adopted by β‐peptides.
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Andrew R. Shaffer Joseph A. R. Schmidt Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(11):2662-2673
Phorteen phine phosphines : Fourteen new α,β‐unsaturated β‐chloroimines were synthesized from inexpensive ketones by using the Vilsmeier–Haack reagent followed by Schiff‐base condensation. Each imine was subsequently converted to an α,β‐unsaturated 3‐iminophosphine through either late‐metal‐catalyzed phosphorus–carbon cross‐coupling or through an addition–elimination sequence (see scheme). This high‐yield protocol serves as a general means to produce α,β‐unsaturated 3‐iminophosphines.
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Andreas Winter Dr. Christian Friebe Manuela Chiper Dr. Ulrich S. Schubert Prof. Dr. Martin Presselt Benjamin Dietzek Dr. Michael Schmitt Dr. Jürgen Popp Prof. Dr. 《Chemphyschem》2009,10(5):787-798
Leading light : A series of zinc(II) bis‐terpyridine complexes (see picture) is investigated by means of DFT calculations combined with Bader's quantum theory of atoms in molecules. Raman spectroscopy experiments and studies of the electro‐optical properties of the complexes in solution and the solid state are also performed to examine their potential as new emissive materials in light‐emitting devices.
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Cuihua Xue Singaravelu Velayudham Steve Johnson Ratul Saha Adrian Smith Wilbel Brewer Pushpalatha Murthy Susan T. Bagley Haiying Liu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(10):2289-2295
Know your bacteria! Two fluorene‐based, conjugated polymers with oligo(ethylene glycol)‐ and poly(ethylene glycol)‐tethered spacers have been prepared by the Suzuki coupling polymerization reactions. β‐Glucose and α‐mannose residues were covalently attached to the conjugated polymers by post‐polymerization functionalization with thiol‐functionalized carbohydrates under basic conditions. Investigations on their use as biosensing materials for the detection of Escherichia coli are reported (see figure).
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Jun Shi Hiroki Shigehisa Dr. Carlos A. Guerrero Ryan A. Shenvi Chuang‐Chuang Li Dr. Phil S. Baran Prof. 《Angewandte Chemie (International ed. in English)》2009,48(24):4328-4331
One stereocenter makes all the difference : The synthesis and biological evaluation of 17‐epi‐cortistatin A is reported from a common intermediate used to procure natural cortistatin A. The synthesis features a unique stereocontrolled Raney‐Ni reduction process that can be employed to reliably produce both α‐ and β‐configured D‐ring aryl steroids. Biological evaluations of these “cortalogs” are reported for the first time.
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Toshiki Nokami Dr. Akito Shibuya Shino Manabe Dr. Yukishige Ito Dr. Jun‐ichi Yoshida Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(10):2252-2255
Low‐temperature electrochemical oxidation of thioglycosides gave glycosyl triflates from which glycosyl sulfonium ions were produced (see scheme). The latter were characterized by NMR spectroscopy and cold‐spray mass spectrometry as a mixture of α‐ and β‐isomers (45:55). The α‐glycosyl sulfonium ion exhibited higher reactivity than the β‐glycosyl sulfonium ion in the reaction with methanol, which gave a mixture of α‐ and β‐methyl glycosides (41:59).
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Takuya Hashimoto Dr. Kazuki Sakata Keiji Maruoka Prof. Dr. 《Angewandte Chemie (International ed. in English)》2009,48(27):5014-5017
Going through the phases : The title reaction was found to proceed by an initial base‐mediated isomerization to allenyl esters and subsequent phase transfer catalyzed alkylation at the α position of the ester (see scheme).
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Peter Höhn Dr. Stefan Hoffmann Dr. Jens Hunger Dr. Stefano Leoni Dr. Fabian Nitsche Dipl.‐Chem. Walter Schnelle Dr. Rüdiger Kniep Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(14):3419-3425
A new page in the phase book : The metastable nitride β‐Ca3N2, the synthesis, crystal structure (see picture), and physical properties of which are reported, is an isotype of corundum (α‐Al2O3). Vacancies in the crystal structure of β‐Ca3N2 are discussed by using full‐potential local orbital methods and taking into account both the physical properties and the density of states.
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Yong‐beom Lim Dr. Kyung‐Soo Moon Myongsoo Lee Prof. 《Angewandte Chemie (International ed. in English)》2009,48(9):1601-1605
Protein roll call : Peptide‐based building blocks, in which both an α‐helix‐forming segment and a β‐sheet segment are located within a single macrocyclic structure, self‐assemble into α‐helix‐decorated artificial proteins. This approach provides a starting point for developing artificial proteins that can modulate α‐helix‐mediated interactions occurring in a multivalent fashion.
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Keith A. Stubbs Dr. Matthew S. Macauley David J. Vocadlo Prof. 《Angewandte Chemie (International ed. in English)》2009,48(7):1300-1303
Gal‐PUGNAc (see picture), a highly selective inhibitor for β‐hexosaminidases HEXA and HEXB is cell‐permeable and modulates the activity of HEXA and HEXB in tissue culture, increasing ganglioside GM2 levels. Gal‐PUGNAc should allow the role of these enzymes to be studied at the cellular level without generating a complex chemical phenotype from concomitant inhibition of O‐GlcNAcase.
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Tsuneyuki Kobayashi Hideki Yorimitsu Prof. Dr. Koichiro Oshima Prof. Dr. 《化学:亚洲杂志》2009,4(7):1078-1083
“Co”axing selectivity into isomerization : Treatment of 1‐alkenes with dimethylphenylsilylmethylmagnesium chloride in the presence of a cobalt‐NHC complex in dioxane at 50 °C or higher provides the corresponding (E)‐2‐alkenes selectively. The isomerization is applicable to the stereoselective synthesis of (E)‐crotylsilanes and (E)‐1‐propenylsilanes from the corresponding homoallylsilanes and allylsilanes, respectively.
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Haifeng Yu Dr. Zhengkun Yu Prof. Dr. 《Angewandte Chemie (International ed. in English)》2009,48(16):2929-2933
Let's make 'meri' : Metal‐free direct alkenylation of indoles was realized by acid‐mediated substitution reactions of α‐oxo ketene dithioacetals with indoles in trifluoroacetic acid/dichloromethane, selectively affording β‐indolyl mono‐ and disubstituted α,β‐unsaturated carbonyl compounds (see scheme). Condensation of the indolyl/ketene monothioacetals and guanidine nitrate efficiently produced meridianin derivatives.
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Jinping Chen Dr. Masatoshi Mizumura Hiroshi Shinokubo Prof. Dr. Atsuhiro Osuka Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(24):5942-5949
Two series of BODIPY dyes with substituents either in the α positions or in the β positions and different conjugation lengths were synthesized by means of iridium‐catalyzed borylation and rhodium‐catalyzed Heck‐type addition (see scheme). The α‐ and β‐substituted series show completely different photophysical properties. BODIPY=boron dipyrrin.
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Hai‐Hua Lu Hui Liu Dr. Wei Wu Xu‐Fan Wang Liang‐Qiu Lu Wen‐Jing Xiao Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(12):2742-2746
Economical approach : The first organocatalytic asymmetric intramolecular hydroarylation of phenol‐ and aniline‐derived enals offers one of the most straightforward and atom‐economic approaches to enantioriched chromans and tetrahydroquinolines (up to 96 % ee; see scheme).
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Ludovic Drouin Dr. E. Cristina Stanca‐Kaposta Dr. Priptal Saundh Antony J. Fairbanks Dr. Sebastian Kemper Timothy D. W. Claridge Dr. John P. Simons Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(16):4057-4069
The effect of carbon is subtle but sweet : The flexible C‐linkage in the newly synthesised C‐glycosyl mimetic, Manα(1,6)‐C‐ManαOPh allows OH? π bonding, both in the gas phase and in aqueous solution. This interaction is absent in the O‐linked disaccharide (see figure).
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Taichi Ikeda Dr. Masayoshi Higuchi Dr. Dirk G. Kurth Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(19):4906-4913
Towards polythiophene polyrotaxanes : The β‐substituted terthiophene [2]rotaxanes have been synthesized (see figure). Basic optical and electrochemical properties of the synthesized [2]rotaxanes are also reported.
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Michiko Sasaki Dr. Yuri Shirakawa Masatoshi Kawahata Dr. Kentaro Yamaguchi Prof. Dr. Kei Takeda Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(14):3363-3366
Brooked up! Treatment of (R,Z)‐3‐(tert‐butyldimethylsilyl)‐1‐cyano‐3‐hydroxyprop‐1‐enyl carbamate with a catalytic amount of a base afforded (S,E)‐3‐(tert‐butyldimethylsilyloxy)‐1‐cyanoallyl diisopropylcarbamate, showing that SE2′‐type reaction of allylsilicates proceeds in an anti fashion. The overall process is equivalent to trapping of an enantioenriched C‐chiral carbanion at the α‐position of nitrile group in up to 77 % ee (see scheme).