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  • Organic Chemistry  (8)
  • scleraxis  (2)
  • Wiley-Blackwell  (10)
  • Nature Publishing Group
  • 1
    Electronic Resource
    Electronic Resource
    Medium-sized cyclophanes, 37.Part 36: Ref.[1]. [n.2]metacyclophanediquinones: Synthesis, conformational studies and reduction to tetrahydroxy[n.2]metacyclophanes (1995)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1995 (1995), S. 995-1001 
    Details
    ISSN: 0947-3440
    Keywords: [n.2]Metacyclophanes, hydroxy- ; Thallium oxidation ; [n.2]Metacyclophanediquinones ; anti and syn Conformers ; Ring inversion ; Hydrogen bonding, intramolecular ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The title compounds, [n.2]metacyclophanediquinones 6a-f, were prepared by oxidation of the corresponding di-tert-butyldihydroxy[n.2]metacyclophanes 5a-f with Tl(OCOCF3)3 in CF3COOH. When [n.2]quinonophanes 6a-e were reduced with Zn powder in acetic acid, the corresponding tetrahydroxy derivatives 8a-e were obtained, which were converted to the tetraacetates 9a-e. The solution conformations of diquinones 6a-f and tetrahydroxy[n.2]MCPs 8a-e are sensitive to the chain length of the bridges. The ring inversion barriers determined by variable-temperature 1H-NMR spectroscopy decrease with increasing length of the bridges. In addition, a solvent effect on the ratio of anti to syn conformers was found to occur in tetrahydroxy[6.2]metacyclophane 8d and dihydroxy[6.2]metacyclophanes 5d, 10d, and 12d. The conformationally rigid tetraacetoxy[n.2]metacyclophanes 9 exhibit fixed „anti“ and „syn“ conformations. The anti and syn ratio is strongly governed by the number of methylene bridges. Thus, a anti-to-syn ratio of the tetraacetoxy[5.2]- (9c) and -[6.2]metacyclophane (9d) differing from that of the tetraols 8c and 8d was obtained. This difference is due to the ring inversion of 8c and 8d. The assignment of anti and syn conformations was confirmed by 1H-NMR analyses. The dynamics of the ring inversion is also discussed.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.1995199506141
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  • 2
    Electronic Resource
    Electronic Resource
    Scleraxis messenger ribonucleic acid is expressed in C2C12 myoblasts and its level is down-regulated by bone morphogenetic protein-2 (BMP2) (1997)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 67 (1997), S. 66-74 
    Details
    ISSN: 0730-2312
    Keywords: scleraxis ; C2C12 myoblasts ; mRNA ; BMP2 ; HLH-type transcription factor ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: We examined the mRNA expression of scleraxis, a non-myogenic helix-loop-helix type transcription factor in C2C12 myogenic cells. Scleraxis mRNA has been shown to be expressed in sclerotome and perichondrium of the embryos. We found that C2C12 cells express 1.2 kb scleraxis mRNA constitutively. Since BMP was reported to induce ectopic bone formation when implanted in muscle, we examined the effects of BMP on scleraxis expression. Scleraxis mRNA expression in C2C12 cells was suppressed by the treatment with BMP2. This suppression was observed at 200 ng/ml but not at the lower concentrations. BMP2 treatment suppressed scleraxis mRNA level within 24 h and lasted at least up to 48 h. Electrophoresis mobility shift assay showed that the proteins in the crude nuclear extracts prepared from C2C12 cells bound to an Scx-E-box sequence, CATGTG, which is preferentially recognized by scleraxis. This binding was competed out by 100-fold molar excess of cold Scx-E-box sequence but not by the one with mutations in the E-box. This band was supershifted by the addition of antiserum raised against scleraxis. BMP2 treatment suppressed the Scx-E binding activity in C2C12 cells. This suppression of the Scx-E-box binding activity was in parallel to the BMP2 suppression of the transcriptional activity of the Scx-E-CAT reporter gene transfected into C2C12 cells. These data indicated that although the default pathway for C2C12 cells is to differentiate into muscle cells, these cells do express non-myogenic transcription factor, scleraxis, whose expression is suppressed by BMP2. J. Cell. Biochem. 67:66-74, 1997. © 1997 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    Fibroblast growth factor downregulates expression of a basic helix-loop-helix-type transcription factor, scleraxis, in a chondrocyte-like cell line, TC6 (1998)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 70 (1998), S. 468-477 
    Details
    ISSN: 0730-2312
    Keywords: scleraxis ; transcription factor ; FGF ; chondrocyte ; bHLH ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Scleraxis is a basic helix-loop-helix-type transcription factor that is expressed in sclerotome. Fibroblast growth factor (FGF) is one of the cytokines produced by the cells in skeletal tissues and is a potent modulator of skeletogenesis. The aim of this study was to examine the effects of FGF on the expression of scleraxis in chondrocyte-like cells, TC6. In these cells, scleraxis mRNA was constitutively expressed as a 1.2kb message at a high level in contrast to its low levels of expression in fibroblast-like cells or osteoblast-like cells. Upon treatment with FGF, scleraxis mRNA level was decreased within 12 h. This effect was at its nadir at 24 h and the scleraxis mRNA level returned to its base line level by 48 h. The FGF effect was maximal at 1 ng/ml. FGF effects on scleraxis were blocked by actinomycin D but not by cycloheximide, suggesting the involvement of transcriptional events that do not require new protein synthesis. The FGF effects on scleraxis were blocked by genistein, suggesting the involvement of tyrosine kinase in the post-receptor signaling. TGFβ treatment of TC6 cells enhanced scleraxis mRNA expression; however, combination of the saturation doses of FGF and TGFβ resulted in suppression of scleraxis mRNA level. BMP2 also suppressed scleraxis mRNA expression in TC6 cells and no further suppression was observed in combination with FGF. These results indicate that scleraxis is expressed in chondrocyte-like TC6 cells and it is one of the targets of FGF action in these cells. J. Cell. Biochem. 70:468-477. © 1998 Wiley-Liss, Inc.
    Additional Material: 8 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    Reactions of Chiral 2-(tert-Butyl)-2H,4H-1,3-dioxin-4-ones Bearing Functional Groups in the 6-Position and Diastereoselective Catalytic Hydrogenation to cis-2,6-Disubstituted 1,3-Dioxan-4-ones (1987)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 70 (1987), S. 2137-2145 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (R)-5-Bromo-6-(bromomethyl)-2-(tert-butyl)-2H,4H-1,3-dioxin-4-one (2) derived from (R)-3-hydroxybutanoic acid is used for substitutions and chain elongations at the side-chain C-atom in the 6-position of the heterocycle (→3-6, 10-13). Subsequent simultaneous reductive debromination and double-bond hydrogenation (Pd/C,H2)occurs with essentially complete diastereoselectivity (〉98% ds), with H transfer from the face opposite to the t-Bu group (→15-20, Table 1). Hydrolytic cleavages of the dioxanones then lead to enantiomerically pure β-hydroxy-acid derivatives (overall self-reproduction of the stereogenic center of 3-hydroxybutanoic acid or alkylation in the 4-position of this acid with preservation of configuration).
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19870700819
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  • 5
    Electronic Resource
    Electronic Resource
    Crystal Structure of (-)-Corycavinium (+)-10-Camphorsulfonate, a biosynthetic intermediate to hexahydrobenzo[c]phenanthridine alkaloids (1994)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 77 (1994), S. 243-251 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The crystal structure of (-)-corycavinium (+)-10-camphorsulfonate has been investigated by X-ray analysis. The structure of (-)-corycavinium ion ( = (-)-(7S,13S,14R)-5,6,13,13a-tetrahydro-13a-hydroxy-7-methyl-2,3;9,10-bis(methylenedioxy)-8H-dibenzo[a,g]quinolizinium), has been determined. The conformation with B/C-cis-conjunction, a twisted half-chair of ring B, and a half-chair of ring C, as well as α-oriented substituted groups N…Me, C…Me, and C…OH is revealed. Feeding experiments with cell suspension cultures of Corydalis incisa (Papaveraceae) defined the intermediacy of (-)-corycavinium in the route from protoberberine-type to hexahydrobenzo[c]phenanthridine-type of alkaloids. On the basis of the present crystal conformation, the stereospecificity of the relating enzyme is biogenetically considered.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19940770126
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  • 6
    Electronic Resource
    Electronic Resource
    X-Ray Crystallographic and MO Studies on the Conformation of Corynoline and the Related Compounds (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 1418-1423 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The crystal structure of (±)-corynoline (1) has been determined by X-ray diffraction methods. The rings B and C form the half-chair and the twist-half-chair conformations, respectively. The B/C ring conjunction exists in an anti-cis conformation, with a N … H—O intramolecular H-bond. Conformational energy calculation by the CNDO/2 method show that the conformations of 1, (+)-chelidonine (2), and their acetates, observed in crystal structures, are all in the one of total energy minimum.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19860690614
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  • 7
    Electronic Resource
    Electronic Resource
    Conformational Features of 7,8,13β,14α-Tetrahydro-N7-methylcorysaminium, a biosynthetic intermediate to the protopine-type alkaloid corycavine (1995)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 78 (1995), S. 80-86 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The crystal structure of (±)-7,8,13β,14α-tetrahydro-N7-(13C)methylcorysaminium iodide (13C-3a·I) was investigated by X-ray analysis and thus the relative configuration (7S*,13S*,14S*) established (Fig. 1). The conformation of 3a was shown to have a cis-junction of the B/C rings and the rings A and D in an antiperiplanar position relative to the C(13)—C(14) bond (‘anti-cis’), a twisted half-chair for ring B, and a half-chair for ring C (Figs. 2 and 3). Conformation analysis by 1H-NMR data indicated that the crystal conformation of 3a is also the preferred one in MeOH solution.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19950780108
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  • 8
    Electronic Resource
    Electronic Resource
    The Preparation and Some Reactions of Unsymmetrical Acyl Thioacyl Sulfides (1981)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981), S. 1798-1811 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Darstellung und einige Reaktionen von unsymmetrischen Acyl(thioacyl)sulfidenDurch Umsetzung von Piperidinium- oder Natrium-dithiocarboxylaten mit Acylchloriden oder durch Entschwefelung von Acyl(thioacyl)disulfiden mit Triphenylphosphan wurden einige un-symmetrische Acyl(thioacyl)sulfide [RC(S)S(O)CR'] dargestellt und charakterisiert. Die tiefblauen Öle oder hellgrünen Kristalle sind thermisch labil und feuchtigkeitsempfindlich. Die n →π-Übergänge der Thiocarbonylgruppe in 1 treten bei höheren Wellenlängen auf als die der entsprechenden symmetrischen Bis(thioacyl)sulfide [RC(S)S(S)CR']. Einige Reaktionen mit Nucleophilen werden diskutiert. Die Umwandlung von unsymmetrischen Acyl(thioacyl)sulfiden in symmetrische Bis(thioacyl)disulfide erfolgt in Gegenwart von Basen wie Lithium-ethanthiolat mit guten Ausbeuten.
    Notes: A number of unsymmetrical acyl thioacyl sulfides [RC(S)S(O)CR'] have been prepared and characterized by the reaction of piperidinium or sodium dithiocarboxylates with acyl chlorides or by desulfurization reaction of acyl thioacyl disulfides with triphenylphosphine. They are deep blue oils or light green crystals and very unstable thermally and for moisture. The n →π transitions of the thiocarbonyl group of 1 appear in higher wave length region than those of the corresponding symmetrical bis(thioacyl) sulfides [RC(S)S(S)CR']. Some reactions with nucleophiles are discussed. It was found that the symmetricallization reaction of these unsymmetrical acyl thioacyl sulfides occurs in the presence of base such as lithium ethanethiolate to give the symmetrical bis(thioacyl) disulfides in fair yield.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198119811008
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  • 9
    Electronic Resource
    Electronic Resource
    Zur Struktur eines neuen Nortriterpens aus den Bulbi von Scilla scilloides Druce1) (1982)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1982 (1982), S. 306-314 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On the Structure of a New Nortriterpene from the Bulbs of Scilla scilloides Druce1)From the acetone extract of the bulbs of Scilla scilloides Druce (Liliaceae) the new nortriterpene 1 has been isolated. The structure of 1 was established on the basis of chemical and spectral evidences. Besides the free state 1 was obtained by mild acid hydrolysis of the acetone-insoluble and methanol-soluble fraction suggesting the existence of 1 also in the form of its glycosides.
    Notes: Aus dem Acetonextrakt der Bulbi von Scilla scilloides Druce (Liliaceae) wurde das neue Nortriterpen 1 isoliert. Auf Grund der chemischen und spektroskopischen Untersuchungen ließ sich die Struktur von 1 ermitteln. Neben dem frei enthaltenen 1 wurde offenbar glycosidisch gebundenes 1 bei der milden Säurehydrolyse der in Aceton unlöslichen und in Methanol löslichen Fraktion erhalten.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198219820214
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  • 10
    Electronic Resource
    Electronic Resource
    Preparation and some reactions of bis(thioacyl) sulfides (1982)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1982 (1982), S. 1229-1244 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Darstellung und einige Reaktionen von Bis(thioacyl)sulfidenDurch Umsetzung von Dithiocarbonsäuren mit Dicyclohexylcarbodiimid wurden die Bis-(thioacyl)sulfide 1, die nützliche und unter milden Reaktionsbedingungen einsetzbare Thioacylierungsmittel sind, dargestellt. Die aliphatischen Thioanhydride (1, R = Aliphaten) sind thermisch labile und feuchtigkeitsempfindliche purpurne öle, die bei Raumtemperatur zu den Dithietanen 5 dimerisieren, während die meisten aromatischen Derivate (1, R = Aromaten) tiefgrüne, einigermaßen stabile Kristalle bilden. Einige Reaktionen mit Nucleophilen werden diskutiert.
    Notes: Reaction of dithioic acids with dicyclohexylcarbodiimide has been found to give the corresponding bis(thioacyl) sulfides 1 in good yield, which are very useful thioacylating reagents under mild reaction conditions. Most of the aromatic thioanhydrides (1, R = aromatic) are fairly stable green crystals at room temperature, but the aliphatic ones (1, R = aliphatic) are unstable purple oils which dimerize at room temperature to give the dithietanes 5. The reactions with nucleophiles are discussed.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198219820702
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