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  • C-C coupling  (11)
  • Wiley-Blackwell  (11)
  • Blackwell Publishing Ltd
  • Elsevier
  • 2000-2004  (11)
Collection
Publisher
  • Wiley-Blackwell  (11)
  • Blackwell Publishing Ltd
  • Elsevier
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Year
  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 1353-1357 
    ISSN: 1434-193X
    Keywords: Heterocycles ; Rearrangements ; C-C coupling ; C-C coupling ; Cyclizations ; Isoquinolines ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -5-Methylbenzo[b]thieno[2,3-c]isoquinolines and 5-methylbenzo[b]seleno[2,3-c]isoquinolines 11b,c have been prepared by Bischler-Napieralski cyclization of 2-acetamido-3-phenylbenzo[b]heteroarenes.
    Additional Material: 4 Tab.
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  • 2
    ISSN: 1434-1948
    Keywords: Carbon dioxide fixation ; Magnesium ; N ligands ; C-C coupling ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of oxalic amidines R1-N=C(NHR2)-C(NHR2)=N-R1 with CH3MgX followed by uptake of CO2 results in the formation of the trimeric carbamato complexes [R1-N=C(NR2-COO)-C(NR2COO)=N-R1]3Mg3(THF)6 (2a: R1 = R2 = Ph; 2b: R1 = R2 = p-tolyl) as the thermodynamically stable final products of the reaction. Their X-ray crystal structures show that the three metal centres are in a linear arrangement. The central magnesium ion is octahedrally surrounded by six O-donor atoms of the μ2-carbamato bridges, while both peripheral magnesium ions are facially coordinated by three O-donor atoms of the carbamato groups and three THF molecules. This coordination sphere can be considered as a structural model for the active centre in the ribulose-1,5-bisphosphate carboxylase/oxygenase enzyme. Compound 2a reacts with ZnCl2 or CoBr2, with CO2 elimination, to form dimeric complexes of the type [X2M(oxalamidinato)MX2][Mg(DMF)6] (M = Zn, Co; X = Cl, Br). X-ray crystal structure analyses show that the d-metals are tetrahedrally coordinated. The magnesium-bromide-containing intermediates in the formation of 2a and 2b are able to transfer CO2 to acetophenone, thus simulating the CO2 activation step in enzymatic biotin-dependent carboxylation reactions.
    Additional Material: 7 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 1959-1964 
    ISSN: 1434-193X
    Keywords: C-C coupling ; Palladium ; Silanes ; Catalysts ; Allylsilanes ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---One of the main problems of the Heck reaction using acyclic substrates which lead to Pd intermediates with β- and β′-hydrogens is the lack of selectivity in the formation of the double bond as the last step of the catalytic cycle. The use of allylsilanes as the alkene moiety permits control of the elimination step. Thus, the Pd0-catalysed reaction of 1a-c and 2 leads exclusively to the corresponding bicyclic compounds 11a-c. In contrast, reaction of 7 yields a mixture of 12a, (E)-12b and (Z)-12b.
    Additional Material: 1 Tab.
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 125-132 
    ISSN: 1434-193X
    Keywords: Aldol condensations ; Carbohydrates ; C-C coupling ; Isomerases ; Controlled ozonolysis ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---A short enzymatic route for the synthesis of L-fucose analogs modified at the nonpolar terminus is reported. In particular, fucose derivatives bearing extended linear (1b) and branched (1e) saturated, or various unsaturated (1c, 1d) aliphatic chains have been prepared, in order to increase hydrophobic contacts. The rather general approach involves a sequential application of the recombinant enzymes L-fuculose 1-phosphate aldolase (FucA) and L-fucose ketol isomerase (FucI) from E.coli. Enantiomerically pure L-fucose analogs have been prepared in up to 30% overall yield starting from the appropriate hydroxyaldehyde precursors and dihydroxyacetone phosphate as readily available components. Unsaturated 2-hydroxyaldehydes have been efficiently prepared by alk(en/yn)yl Grignard addition to cinnamaldehyde followed by controlled ozonolysis of the styrene fragment.
    Additional Material: 1 Ill.
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  • 5
    ISSN: 1434-193X
    Keywords: Macrocycles ; Palladium ; Polymers ; Catalysis ; C-C coupling ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Preparation of the 15-membered cycle (E,E,E)-1,6,11-tris[(2,4,6-triisopropylphenyl)sulfonyl]-1,6,11-triazacyclopentadeca3,8,13-triene (8) is reported. This cyclic triolefin forms a stable Pd0 complex 9 which catalyzes several cross-coupling reactions and can be recovered. Anchoring to a polystyrene framework affords a solid version of the catalyst, which is recovered by simple filtration and reused without loss of catalytic activity.
    Additional Material: 2 Tab.
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 1827-1830 
    ISSN: 1434-193X
    Keywords: C-C coupling ; Homosteroids ; Palladium ; Steroids ; Total synthesis ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The D-homosteroid 1 was synthesized by two successive Heck reactions starting from enantiopure 3 and the bromoarene 2 containing a (Z)-bromovinyl group. The first intermolecular Pd-catalyzed reaction leads to 6 in a highly regio- and diastereoselective way which forms 1 with an unusual cis-junction of the rings B and C by a second intramolecular Heck reaction.
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  • 7
    ISSN: 1434-193X
    Keywords: Aplykurodins ; Marine steroids ; C-C coupling ; Cyclic peroxides ; Lactonization ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---An approach to the synthesis of aplykurodins, ichthyotoxic marine lactones, is presented. The carbon framework was derived from vitamin D3 by conversion of the readily accessible allyl alcohol 13 to the protected Grundmann's hydroxy ketone 22 and subsequent introduction of the C2 side chain through a Pd0-promoted coupling. Highly stereoselective hetero Diels-Alder reaction with O21 produced the key intermediate peroxide 25. Functional group transformations, coupled with a series of chemo- and stereoselective reactions, finally resulted in the synthesis of the unnatural analogue 17,18-dihydro-3,9-di-epi-aplykurodinone B (6).
    Additional Material: 2 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 939-946 
    ISSN: 1434-193X
    Keywords: Enediynes ; Vanadium ; C-C coupling ; Macrocycles ; Lactams ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---A short synthesis of unfunctionalized lactenediyne 3 by closure of the ten-membered ring at the double bond site is reported. After failure of the known methodologies, this closure was eventually successfully achieved thanks to a highly stereoselective, vanadium(II)-mediated pinacol coupling of bis(alk-2-ynal) 7.Supporting information for this article is available on the WWW under //http://www.wiley-vch.de/contents/jc_2046/2000/99471_s.pdf or from the author.
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  • 9
    ISSN: 1434-193X
    Keywords: Cyclophanes ; Myricanone ; Diaryls ; C-C coupling ; Dinitriles ; Condensation reactions ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The syntheses of the diaryls 14 and 21, substituted by two ω-cyanoalkyl chains (one on each ring), are described. Treatment of the unsymmetrical diaryl 14 with NaN(Me)Ph in a Thorpe-Ziegler reaction failed to give any definite product. Under the same conditions the symmetrical diaryl 21 led to an isomeric mixture of dimeric enaminonitriles 24. Mild acidic hydrolysis of the latter yielded the isomeric β-ketonitriles 25, whereas more drastic hydrolytic conditions led to the macrocyclic diketone 26.
    Additional Material: 2 Ill.
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  • 10
    ISSN: 1434-193X
    Keywords: Benzothiazole carbene ; Palladium complex ; Homogeneous catalysis ; C-C coupling ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The first diiodo palladium complex with nucleophilic benzothiazole carbenes as ligands has been synthesized and characterized. The complex, which is extraordinarily stable towards heat, oxygen, and moisture, has been found to show good catalytic activity in the Heck coupling reaction.
    Additional Material: 1 Ill.
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  • 11
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 1313-1317 
    ISSN: 1434-193X
    Keywords: Leishmaniasis ; Natural products ; Phytochemistry ; Quinones ; C-C coupling ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: -The first synthesis of diospyrin [2,6′-bis(5-hydroxy-7-methyl-1,4-naphthoquinone), 1] was achieved by employing Suzuki coupling between 5 and 14 as the key reaction to connect the two 7-methyljuglone units.
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