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  • 1
    ISSN: 1434-193X
    Keywords: Fluorine ; Sulfoxides ; Nucleotide analogues ; Asymmetric synthesis ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: D- and L-(diethoxyphosphoryl)difluoromethyl nucleoside analogues 10 have been synthesized using the building block approach, starting from chiral fluorinated molecules. The key steps of the synthetic sequence were condensation of 2-methyl-5-(4-methylphenylsulfinyl)pent-2-ene (1) and ethyl 2-(diethoxyphosphoryl)-2,2-difluoroacetate (2), reduction of the thus formed ketones 3 to alcohols 4, reductive removal of the sulfur moiety to give hydroxy phosphonates 6, and oxidative cyclization to give furanose derivatives 8.
    Additional Material: 3 Tab.
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  • 2
    ISSN: 1434-193X
    Keywords: Fluorine ; Lactones ; Annulation ; Ketene ; Sulfoxides ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -Enantiomerically pure α,α-dichloro β-fluoroalkyl γ-p-tolylthio γ-butyrolactones trans-6a-c have been obtained with excellent stereocontrol (〉 98:2) and enantiomeric purity (〉 98:2) by sulfoxide-directed lactonization (Marino's annu-lation reaction) of β-fluoroalkyl vinyl sulfoxides (R)-(E)-5a-c with dichloroketene. Highly chemoselective dechlorination and desulfurization reactions performed on trans-6c efficiently provided the β-chlorodifluoromethyl γ-butyrolactone (S)-8c, the absolute stereochemistry of which was determined by X-ray diffraction analysis of its γ-p-tolylthio precursor (2R,3S)-7c.
    Additional Material: 1 Ill.
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  • 3
    ISSN: 1434-193X
    Keywords: β-Iminosulfoxides ; Quaternary stereocentre ; Pictet-Spengler reaction ; Alkaloids ; Fluorine ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Enantiomerically pure 1-trifluoromethyl-tetrahydroisoquinoline alkaloid analogues, in which C-1 is a quaternary stereogenic centre, have been synthesized by stereoselective intramolecular Pictet-Spengler reaction of the N-arylethyl γ-trifluoro-β-iminosulfoxide (R)-3, and subsequent elaborations of the sulfinyl auxiliary. The absolute stereochemistry of the stereogenic centre was determined by X-ray diffraction on the α-phenylpropionic ester (1R,2′S)-10.
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  • 4
    ISSN: 1434-193X
    Keywords: Fluorine ; Pheromones ; Sulfoxides ; Sulcatol ; Asymmetric synthesis ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -The pheromone (R)-(-)-sulcatol (10a) and three of its enantiomeric mono-, di-, and trifluoro analogues 10b-d have been synthesized, in six steps and with good overall yields, starting from chiral (R)-2-methyl-5-[(4-methylphenyl)sulfinyl]pent-2-ene (1) and commercially available fluorinated or non-fluorinated acetates.Supporting information for this article is available on the WWW under http://www.wileY-Vch.de/contents/jc_2046/1999/98375_s.pdf or from the author.
    Additional Material: 2 Tab.
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  • 5
    ISSN: 1434-193X
    Keywords: Fluorine ; Cycloadditions ; Nitrones ; Asymmetric induction ; Sulfoxides ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 3-(Fluoroalkyl)isoxazolidines 6 and -2,3-dihydroisoxazoles 8 have been obtained in enantiomerically pure form with good diastereoselectivity by 1,3-dipolar cycloaddition of diethyl fumarate and dimethylacetylene dicarboxylate, respectively, to the chiral fluorinated nitrone (R)-5. The latter has been prepared from the β-fluoromethyl-β-oxo sulfoxide (RS)-1, by a synthetic sequence where the chiral and enantiomerically pure sulfinyl function acts as a removable source of chirality. Reductive opening of isoxazolidines 6 then afforded amino fluoromethyl diols 7 in good yields.
    Additional Material: 1 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 1387-1389 
    ISSN: 1434-193X
    Keywords: Natural products ; Epoxidations ; Asymmetric synthesis ; Fluorine ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The synthesis of enantiomerically and diastereomerically pure (-)-(1R,2R,5R)- and (-)-(1R,2S,5R)-2-fluoro frontalin (7) starting from (+)-(1S)-menthyl-(R)-toluene-4-sulfinate, methylmagnesium bromide, methyl fluoroacetate, 4-pentenyl bromide and diazomethane is described. The absolute stereochemistry was unambiguously determined by X-ray analysis of (+)-(1S,2R,5S,RS)-5, an intermediate in the synthesis of the enantiomeric (+)-(1S,2R,5S)-2-fluoro frontalin (7).
    Additional Material: 2 Ill.
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  • 7
    Publication Date: 2008-07-03
    Description: Reprogramming of somatic cells is a valuable tool to understand the mechanisms of regaining pluripotency and further opens up the possibility of generating patient-specific pluripotent stem cells. Reprogramming of mouse and human somatic cells into pluripotent stem cells, designated as induced pluripotent stem (iPS) cells, has been possible with the expression of the transcription factor quartet Oct4 (also known as Pou5f1), Sox2, c-Myc and Klf4 (refs 1-11). Considering that ectopic expression of c-Myc causes tumorigenicity in offspring and that retroviruses themselves can cause insertional mutagenesis, the generation of iPS cells with a minimal number of factors may hasten the clinical application of this approach. Here we show that adult mouse neural stem cells express higher endogenous levels of Sox2 and c-Myc than embryonic stem cells, and that exogenous Oct4 together with either Klf4 or c-Myc is sufficient to generate iPS cells from neural stem cells. These two-factor iPS cells are similar to embryonic stem cells at the molecular level, contribute to development of the germ line, and form chimaeras. We propose that, in inducing pluripotency, the number of reprogramming factors can be reduced when using somatic cells that endogenously express appropriate levels of complementing factors.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kim, Jeong Beom -- Zaehres, Holm -- Wu, Guangming -- Gentile, Luca -- Ko, Kinarm -- Sebastiano, Vittorio -- Arauzo-Bravo, Marcos J -- Ruau, David -- Han, Dong Wook -- Zenke, Martin -- Scholer, Hans R -- England -- Nature. 2008 Jul 31;454(7204):646-50. doi: 10.1038/nature07061. Epub 2008 Jun 29.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Cell and Developmental Biology, Max Planck Institute for Molecular Biomedicine, Rontgenstrasse 20, 48149 Munster, NRW, Germany.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18594515" target="_blank"〉PubMed〈/a〉
    Keywords: Adult Stem Cells/*cytology/metabolism ; Animals ; Cell Differentiation/genetics ; Cells, Cultured ; *Cellular Reprogramming ; Chimera ; DNA-Binding Proteins/genetics/metabolism ; Female ; Gene Expression Profiling ; Genes, myc/genetics ; HMGB Proteins/genetics/metabolism ; Homeodomain Proteins/genetics ; Kruppel-Like Transcription Factors/genetics/metabolism ; Male ; Mice ; Mice, Nude ; Mice, Transgenic ; Neurons/*cytology ; Octamer Transcription Factor-3/genetics/metabolism ; Pluripotent Stem Cells/*cytology/*metabolism ; Proteins/genetics ; Proto-Oncogene Proteins c-myc/metabolism ; RNA, Untranslated ; SOXB1 Transcription Factors ; Transcription Factors/genetics/metabolism ; Transduction, Genetic
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 8
    Publication Date: 2009-09-01
    Description: Induced pluripotent stem (iPS) cells have been generated from mouse and human somatic cells by ectopic expression of four transcription factors (OCT4 (also called POU5F1), SOX2, c-Myc and KLF4). We previously reported that Oct4 alone is sufficient to reprogram directly adult mouse neural stem cells to iPS cells. Here we report the generation of one-factor human iPS cells from human fetal neural stem cells (one-factor (1F) human NiPS cells) by ectopic expression of OCT4 alone. One-factor human NiPS cells resemble human embryonic stem cells in global gene expression profiles, epigenetic status, as well as pluripotency in vitro and in vivo. These findings demonstrate that the transcription factor OCT4 is sufficient to reprogram human neural stem cells to pluripotency. One-factor iPS cell generation will advance the field further towards understanding reprogramming and generating patient-specific pluripotent stem cells.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kim, Jeong Beom -- Greber, Boris -- Arauzo-Bravo, Marcos J -- Meyer, Johann -- Park, Kook In -- Zaehres, Holm -- Scholer, Hans R -- England -- Nature. 2009 Oct 1;461(7264):649-3. doi: 10.1038/nature08436.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Max Planck Institute for Molecular Biomedicine, Department of Cell and Developmental Biology, Rontgenstrasse 20, 48149 Munster, NRW, Germany.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19718018" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Biomarkers/analysis ; *Cell Dedifferentiation ; Cell Differentiation ; Cell Line ; *Cellular Reprogramming ; DNA Methylation ; Embryonic Stem Cells/cytology/metabolism ; Epigenesis, Genetic ; Fetus/*cytology ; Gene Expression Profiling ; Germ Layers/cytology/metabolism ; Humans ; Mice ; Neurons/*cytology/metabolism ; Octamer Transcription Factor-3/genetics/*metabolism ; Pluripotent Stem Cells/*cytology/*metabolism
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 9
    Publication Date: 2007-11-03
    Description: The evolution of insect resistance threatens the effectiveness of Bacillus thuringiensis (Bt) toxins that are widely used in sprays and transgenic crops. Resistance to Bt toxins in some insects is linked with mutations that disrupt a toxin-binding cadherin protein. We show that susceptibility to the Bt toxin Cry1Ab was reduced by cadherin gene silencing with RNA interference in Manduca sexta, confirming cadherin's role in Bt toxicity. Native Cry1A toxins required cadherin to form oligomers, but modified Cry1A toxins lacking one alpha-helix did not. The modified toxins killed cadherin-silenced M. sexta and Bt-resistant Pectinophora gossypiella that had cadherin deletion mutations. Our findings suggest that cadherin promotes Bt toxicity by facilitating toxin oligomerization and demonstrate that the modified Bt toxins may be useful against pests resistant to standard Bt toxins.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Soberon, Mario -- Pardo-Lopez, Liliana -- Lopez, Idalia -- Gomez, Isabel -- Tabashnik, Bruce E -- Bravo, Alejandra -- 1R01 AI066014/AI/NIAID NIH HHS/ -- New York, N.Y. -- Science. 2007 Dec 7;318(5856):1640-2. Epub 2007 Nov 1.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Instituto de Biotecnologia, Universidad Nacional Autonoma de Mexico, Apartado Postal 510-3, Cuernavaca 62250, Morelos, Mexico. mario@ibt.unam.mx〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/17975031" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Bacterial Proteins/chemistry/*genetics/metabolism/*toxicity ; Bacterial Toxins/chemistry/*genetics/metabolism/*toxicity ; Cadherins/genetics/metabolism ; Endotoxins/chemistry/*genetics/metabolism/*toxicity ; Genetic Engineering ; Hemolysin Proteins/chemistry/*genetics/metabolism/*toxicity ; *Insecticide Resistance ; Larva ; *Manduca/genetics/metabolism ; *Moths/genetics/metabolism ; Mutation ; *Pest Control, Biological ; RNA Interference
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 10
    Publication Date: 2012-12-22
    Description: Modern attempts to produce biogeographic maps focus on the distribution of species, and the maps are typically drawn without phylogenetic considerations. Here, we generate a global map of zoogeographic regions by combining data on the distributions and phylogenetic relationships of 21,037 species of amphibians, birds, and mammals. We identify 20 distinct zoogeographic regions, which are grouped into 11 larger realms. We document the lack of support for several regions previously defined based on distributional data and show that spatial turnover in the phylogenetic composition of vertebrate assemblages is higher in the Southern than in the Northern Hemisphere. We further show that the integration of phylogenetic information provides valuable insight on historical relationships among regions, permitting the identification of evolutionarily unique regions of the world.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Holt, Ben G -- Lessard, Jean-Philippe -- Borregaard, Michael K -- Fritz, Susanne A -- Araujo, Miguel B -- Dimitrov, Dimitar -- Fabre, Pierre-Henri -- Graham, Catherine H -- Graves, Gary R -- Jonsson, Knud A -- Nogues-Bravo, David -- Wang, Zhiheng -- Whittaker, Robert J -- Fjeldsa, Jon -- Rahbek, Carsten -- New York, N.Y. -- Science. 2013 Jan 4;339(6115):74-8. doi: 10.1126/science.1228282. Epub 2012 Dec 20.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Center for Macroecology, Evolution, and Climate, Department of Biology, University of Copenhagen, 2100 Copenhagen O, Denmark.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23258408" target="_blank"〉PubMed〈/a〉
    Keywords: Amphibians/classification ; Animals ; Birds/classification ; *Climate ; Mammals/classification ; *Phylogeny ; Phylogeography
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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