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  • 1995-1999  (7)
  • 1985-1989  (7)
  • 1975-1979  (4)
  • 1
    Electronic Resource
    Electronic Resource
    Bicyclopropylidene: cycloadditions onto a unique olefin (1988)
    s.l. : American Chemical Society
    The @journal of organic chemistry 53 (1988), S. 152-161 
    Details
    ISSN: 1520-6904
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/jo00236a031
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Analysis of an alternatively spliced exon of the neurofibromatosis type 1 gene in cultured melanocytes from patients with neurofibromatosis 1 (1995)
    Springer
    Archives of dermatological research 287 (1995), S. 413-416 
    Details
    ISSN: 1432-069X
    Keywords: Neurofibromatosis type 1 (NF1) ; Melanocyte culture ; NF1 Gene ; Café-au-lait macules
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Neurofibromatosis type 1 (NF1) is characterized by clinical features that primarily affect tissues derived from the neural crest (neurofibromas, café-au-lait macules). Because aberrant regulation of alternative splicing in the NF1 gene transcript may be of functional significance, cultured melanocytes from café-au-lait macules (CALM), as an example of benign NF1 lesions, were examined for the expression of the different alternative splice products of this gene. Both kinds of NF1 messengers (type 1 and 2) were found not only in CALM melanocytes but also in keratinocytes, fibroblasts and blood cells. Except in blood cells, there was a predominance of the type 2 transcript. Melanocytes from NF1 patients and healthy donors showed similar expression patterns under several culture conditions. Our results suggest that the development of CALM does not correlate with a switch in the ratio of type 1 to type 2 NF1 messenger RNA.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00373420
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  • 3
    Electronic Resource
    Electronic Resource
    Two novel mutations in exons 19a and 20 and a BsaI polymorphism in a newly characterized intron of the neurofibromatosis type 1 gene (1998)
    Springer
    Human genetics 〈Berlin〉 102 (1998), S. 367-371 
    Details
    ISSN: 1432-1203
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Neurofibromatosis type 1 (NF1) is a common autosomal dominant disorder. It is caused by mutations in the NF1 gene, which comprises 60 exons and is located on chromosome 17q11.2. A total of 170 unrelated NF1 patients were screened for mutations in four exons by temperature-gradient gel electrophoresis. Preparatory work revealed the presence of a previously uncharacterized intron (19a) in what was previously designated exon 19; this allowed us to develop assays for genomic mutation screening in the newly defined exons 19a and 19b. Two novel NF1 mutations were detected: a single-base insertion in exon 19a creating a frameshift, and a second mutation affecting the splice donor site of intron 20 and leading to skipping of exon 20. A novel BsaBI polymorphism was identified in intron 19a.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004390050706
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  • 4
    Electronic Resource
    Electronic Resource
    Two recurrent nonsense mutations and a 4 bp deletion in a quasi-symmetric element in exon 37 of the NF1 gene (1995)
    Springer
    Human genetics 〈Berlin〉 96 (1995), S. 95-98 
    Details
    ISSN: 1432-1203
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract We screened a total of 92 unrelated patients with neurofibromatosis type 1 (NF1) for mutations in exon 37 of the NF1 gene, by using temperature gradient gel electrophoresis. Two novel mutations were found: a 4 bp deletion in a so-called quasi-symmetric element (6789delTTAC) and a recurrent nonsense mutation, which was identified in two unrelated patients, at codon 2264 (C6792A). The independent origin of the latter mutation in two families was confirmed by haplotype analysis. The nonsense mutation and the 4 bp deletion are both predicted to lead to a truncated protein product lacking the Cterminal 20% (aproximately) of its sequence. The occurrence of three independent mutations among 92 NF1 patients at codons 2263–2264 (exon 37) suggests that a specific search for mutations in this area should be undertaken in screening programs for NF1 mutations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00214193
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  • 5
    Electronic Resource
    Electronic Resource
    Blitzvakuumpyrolyse von o-Alkylaryl- und Arylalkylchlorboranen Synthese benzoanellierter Boracycloalkene (1987)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 120 (1987), S. 1331-1338 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Flash Vacuum Pyrolysis Of o-Alkyaryl- and Arylalkylchloroboranes. - Synthesis of Benzoannutated Boracycloalkenes The dichloroorganylboranes chosen as pyrolytic starting materials were synthesized upon treatment of the corresponding triorganylboroxines and aryltrimethylsilanes (giving 3, 4) or the tetraorganylstannanes (giving 9-12, 17-20) with boron trichloride. At 700°C the flash vacuum pyrolysis of the dichloro(2-ethylphenyl)boranes 10 and 4 led to 1-boraindanes 21 and 22 selectively. The dichloro-2-tolylborane (9), the B-dimethylamino derivative, and mesitylboranes like 3 were completely stable upon pyrolysis. Pyrolyzing the isopropylphenylborane 12 1,5-elimination exclusively took place yielding 26, while pyrolysis of propylphenylborane 11 led to a mixture of boraindane 29 and boratetraline 30. To exclude such competitive reactions, some arylalkyldichloroboranes were pyrolyzed. At 750°C dichloro(2-methylbenzyl)borane (18) exclusively yielded oligomeric 2-chloro-2-boraindane (31). At 950°C even the pyrolysis of benzyldichloroborane (17) succeeded in a 1,4-elimination reaction yielding the eight-membered 2H-benzoborete dimer 34. The inversion barrier of 34 is ΔG228=10.3 kcal mol-1, determined by NMR spectroscopy. The pyrolysis of the next-higher homologous dichloroorganylborane 19 yielded a boraindane 21 and a noncyclic diorganylborane 38 by a dehydroboration/hydroboration pathway. Both reaction types also took place when pyrolyzing dichloro[2-(2-tolyl)ethyl]borane (20): cyclization under formation of a five-membered ring system 39, formed upon attack of an aromatic C-H bond exclusively, and formation of an open-chain chlorodiorganylborane 40.
    Notes: Die als Pyrolyse-Edukte eingesetzten Dichlororganylborane wurden durch Umsetzung der entsprechenden Triorganylboroxine und Aryltrimethylsilane (zu 3, 4) oder der Tetraorganylstannane (zu 9-12, 17-20) mit Bortrichlorid gewonnen. Die Blitzvakuumpyrolyse der Dichlor(2-ethylphenyl)borane 10 und 4 führte bei 700°C selektiv zu den 1-Boraindanen 21 und 22. Das Dichlor-2-tolylboran (9) war thermisch ebenso stabil wie das B-Dimethylamino-Derivat und Mesitylborane wie 3. Auch bei der Pyrolyse des Isopropylphenylborans 12 trat ausschließlich 1,5-Eliminierung unter Bildung von 26 ein, während die Pyrolyse des Propylphenylborans 11 zu einem Gemisch aus Boraindan 29 und Boratetralin 30 führte. Um derartige intramolekulare Konkurrenzsituationen auszuschließen, wurden Arylalkyldichlorborane pyrolysiert. Dichlor(2-methylbenzyl)boran (18) lieferte bei 750°C ausschließlich oligomeres 2-Chlor-2-boraindan (31). Bei 950°C reagierte sogar Benzyldichlorboran (17) unter 1,4-Eliminierung zu dem achtgliedrigen 2H-Benzoboret-Dimeren 34. Die Inversionsbarriere von 34 wurde NMR-spektroskopisch zu ΔG228=10.3 kcal mol-1 bestimmt. Die Pyrolyse des nächsthöheren homologen Dichlororganylborans 19 lieferte ein Boraindan (21) und ein nichtcyclisches Diorganylboran 38 über eine Dehydroborierungs-/Hydroborierungsreaktion. Beide Reaktionstypen wurden auch bei der Pyrolyse von Dichlor[2-(2-tolyl)ethyl]boran (20) beobachtet: Cyclisierung ausschließlich unter Fünfringbildung (39) durch Angriff einer aromatischen C-H-Bindung und Bildung eines offenkettigen Chlordiorganylborans (40).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19871200811
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  • 6
    Electronic Resource
    Electronic Resource
    Borylierung von Arylsilanen, I Ein allgemeiner, einfacher und selektiver Zugang zu Phenyldihalogenboranen (1987)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 120 (1987), S. 853-854 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Upon treatment with trihaloboranes 2b-d the phenyltrimethylsilanes 1, 6, 8, and 10 yield the corresponding phenyldihaloboranes 3, 7, 9, and 11 with high selectivity. Benzylsilanes are not attacked.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19871200527
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  • 7
    Electronic Resource
    Electronic Resource
    Borylierung von Arylsilanen, II Synthese und Reaktionen silylierter Dihalogenphenylborane (1987)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 120 (1987), S. 901-905 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Upon treatment with trihaloboranes 4a and 4b the bissilylated benzenes 1, 2, and 3 yield the silylated dihalogenphenylboranes 5a-7b under substitution of one silyl group only. The corresponding difluoroboranes 5c-7c are easily accessible by a new fluorination method under mild reaction conditions by treating the dichloroboranes with lithium fluoride in ether. Upon heating with excess 4 the exchange of the second silyl group occurs, too, yielding the position-isomeric diborylbenzenes 9, 10, and 11. The bromination of the silylated dichlorophenylboranes 5a-7a proceeds with high regioselectivity under desilyation yielding 12, 13, and 14. The dimethoxyboranes 15, 16, and 17, synthesized by methanolysis of the corresponding dichloroboranes, can be coupled with bromobenzene under palladium(O) catalysis to yield the position-isomeric silylated biphenyls 18, 19, and 20.
    Notes: Die zweifach silylierten Benzole 1, 2 und 3 reagieren mit 4a, b unter Ersatz einer Silylgruppe zu den silylierten Dihalogenphenylboranen 5a-7b. Die entsprechenden Difluorborane 5c-7c sind mit einer neuen Fluorierungsmethode leicht zugänglich durch Umsetzung der Dichlorborane mit Lithiumfluorid in Ether. Durch Erhitzen mit überschüssigem 4 gelingt der Austausch der zweiten Silylgruppe unter Bildung der stellungsisomeren Diborylbenzole 9, 10 und 11. Die silylierten Dichlorphenylborane 5a-7a werden regioselektiv unter Desilylierung zu 12, 13 und 14 bromiert. Die durch Methanolyse der Dichlorborane erhaltenen Dimethoxyborane 15-17 lassen sich Palladium(O)-katalysiert mit Brombenzol zu den drei stellungsisomeren silylierten Biphenylen 18-20 kuppeln.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19871200606
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  • 8
    Electronic Resource
    Electronic Resource
    Synthesis and Structure of 2,2′ -Boryl-, Germyl-Silyl-, and Stannyl-Substituted 1,1′ -Binaphthyl SystemsDedicated to Professor Hans Paulsen on the occasion of his 75th birthday. (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 923-932 
    Details
    ISSN: 0009-2940
    Keywords: Biaryls ; Boron ; Chirality ; Cooperative Effects ; Lewis acids ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A number of Lewis acid binaphthyl systems, substituted in 2-or 2,2′-position, are synthesized by lithiation of 2,2′-dibromo-1,l ′-binaphthyl (5), followed by addition of various electrophiles. Stepwise lithiation and subsequent borylation with trimethyl borate leads to the bromoboronic acid 6, which can be stabilized by esterification with pinacol giving 7. By increasing the reaction mixture to 2 equiv. of n-butyllithium and 2 equiv. of methyl borate the path to the binaphthylmonoboronic acid ester 9 is opened up. A further increase in the quantity of electrophile also leads to the binaphthylbisboronic acid ester 12. The 2,2′-disubstituted silyl, germyl, and stannyl derivatives 13a-15a are accessible in good yields. Treatment with boron halides leads exclusively to methyl/halogen exchange, giving the bidentate Lewis acids 13b-15b, the former of which can be bridged by oxygen.Only in case of the bis(tributylstannyl)binaphthyl 16a does ipso substitution occur in the presence of boron trichloride, giving the bis(dichloroboryl)-substituted binaphthyl 16b which can then be hydrolysed to 11. The structures of the majority of the compounds were investigated by X-ray diffraction. In case of the 2,2′-disubstituted compounds 13a-15a the naphthyl groups are orientated perpendicular to each other. The intra- and intermolecular interactions are dominated by this binaphthyl system. In case of the oxygenbridged compounds 13c and 14c the angle between the naphthyl planes decreases to about 70°. This also has an effect on the packing of the molecule; in this instance the orientation of two naphthyl in neighbouring molecules is nearly parallel. The structure of the diboronic acid is dominated by intra- and intermolecular hydrogen bonding.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300718
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  • 9
    Electronic Resource
    Electronic Resource
    Palladium  -  Catalyzed Reactions, 1 Palladium-Catalyzed Enantioselective Hydrophenylation and Hydrohetarylation of Bicyclo[2.2.1]Hept-2-ene: Influence of the Chiral Ligand, the Leaving Group, and the Solvent (1997)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 130 (1997), S. 1327-1331 
    Details
    ISSN: 0009-2940
    Keywords: Asymmetric catalysis ; Hydroarylation ; Palladium ; P-N ligands ; Heterocycles ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The use of optically active biaryl bisphosphanes 10-12, a diphenylphosphanylphenyloxazoline 8, and a (β-N-sulfonyl-aminomethyl)bisdiphenylphosphane 7 as ligands in the Pd-catalyzed Heck-type hydroarylation of norbornene (1) with phenyl 2 and various hetaryl derivaties 3-5 leads exclusively to the formation of exo-2(het)arylnorbornanes 6 with asymmetric inductions of up to 86.4% ee. In addition to an investigation into the effects of different chiral ligands, a systematic study has been made of the influence of various (het)aryl compounds, leaving groups, and solvents on the chemical and optical yields of this reductive arylation.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19971300924
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  • 10
    Electronic Resource
    Electronic Resource
    Borylierung von Arylsilanen, III Reaktionen silylierter Biphenyle und 9H-9-Silafluorene mit Tribromboran (1987)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 120 (1987), S. 991-994 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Treatment of tribromoborane (9) with the 3-, 4-, and 4,4′ -silylated biphenyls 7, 8, and 18 leads to substitution of the silyl groups with formation of the aryldibromoboranes 10, 11, and 19, whereas depending on the solvent the 2-iomers 12 and 4 suffer methyl abstraction to predominatly yield 14 and 20. The reaction of the silafluorene 15 with 9 exclusively leads to the dibenzoborole 16. In the first step of the reaction of the 2,2′,3,3′-tetrakissilylated biphenyl 6 with 9 the bissilylated silafluorene 21 is formed, in the second a twofold abstraction of a methyl group yields 22, as the central dimethylsilylene group is too much shielded for an exchange reaction. 22 is a well suited building block for constructing cyclic oligosilanes.
    Notes: Von den silylierten Biphenylen reagieren das 3-(7) und die 4-bzw. 4,4′-Isomeren (8, 18) mit Tribromboran (9) glatt unter Ersatz der Trimethylsilygruppen zu den Aryldibromboranen 10, 11 und 19, während bei dem 2-(12) bzw. 2,2′-Isomeren (4) lösungsmittelabhängig überwiegend Methylabspaltung unter Bildung von 14 bzw. 20 eintritt. Das Silafluoren 15 regiert mit 9 dagegen ausschließlich zum Dibenzoborol 16. Die Umsetzung des 2,2′,3,3′-tetrakissilylierten Biphenyls 6 mit 9 führt zuerst zu dem zweifach silylierten Silafluoren 21, dann jedoch unter zweifacher Methylabspaltung zu 22, da die zentrale Dimethylsilyleneinheit für einen Austausch sterisch zu sehr abgeschirmt ist. 22 ist ein geeigneter Baustein zum Aufbau von Oligosilacyclen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19871200617
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