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  • 1
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 57 (2001), S. o502-o504 
    ISSN: 1600-5368
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: The title compound, C13H14N4O, has been synthesized as an ADDA (D: hydrogen-bond donor; A: hydrogen-bond acceptor) recognition unit for quadruple hydrogen bonds. In the solid state, it crystallizes as a centrosymmetric dimer connecting one N—H group with one pyridyl N atom. Furthermore, an intramolecular hydrogen bond is formed connecting two N atoms.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 24 (1996), S. 43-60 
    ISSN: 1573-1111
    Keywords: Pyridine ; 1,10-phenanthroline ; selectivity ; macrocycle ; concave reagents
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract By incorporating standard organic reagents into a concave environment one can synthesize concave reagents. Their geometry resembles that of a light bulb in a lampshade. In protonations, base catalyses and metal ion catalyzed reactions the concave shielding leads to selectivity enhancements.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford [u.a.] : International Union of Crystallography (IUCr)
    Acta crystallographica 57 (2001), S. 989-990 
    ISSN: 1600-5759
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: The title compound, C15H20N4O, has been synthesized as an AADD recognition unit for quadruple hydrogen bonds. All non-H atoms of the molecule apart from two methyl groups of the tert-butyl group lie in a common plane. An intramolecular hydrogen bond is formed connecting two N atoms. In the solid state, the title compound crystallizes as a centrosymmetric dimer connected by N—H...O=C interactions with an N...O distance of 2.824 (2) Å.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 35 (1999), S. 381-387 
    ISSN: 1573-1111
    Keywords: allylation ; calixarenes ; concave reagents ; cyclopropanation ; dendrimers ; metal ion catalysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The concave shielding of the active site of enzymes has been transferred to standard reagents of organic chemistry and concave reagents have been synthesized which possess a lamp-like geometry (concave 1,10-phenanthrolines 1–2, concave pyridines 3). The special concave geometry of these reagents is responsible for their selectivity in metal ion catalyzed (Pd-catalyzed allylations, Cu(I)-catalyzed cyclopropanations) and base catalyzed (acylation of alcohols by ketenes) reactions. For an easier recovery, these reagents have been attached to Merrifield polymers and to dendrimers. Higher generations of dendrimers loaded with concave reagents will possess a golf ball geometry.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1996 (1996), S. 2099-2105 
    ISSN: 0947-3440
    Keywords: Bimacrocycle ; Base catalysis ; Hydrogen bond ; Molecular recognition ; Pyridine ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Concave pyridines 1 were used to catalyze the addition of primary and secondary alcohols to ketenes 4, and the kinetic data of these catalyses were determined. In inter- and intramolecular competitions the use of 1e-g led to improved selectivities for the acylation of primary alcohols in comparison with secondary alcohols. All primary alcohols react at comparable rates. Observed rate constants were correlated with Taft's Es values. The starting materials and products were fully characterized.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 117 (1984), S. 859-861 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of γ- and δ-Lactones via Radical CC-Bond Formation ReactionLactones 5 and 6 can be synthesized via solvomercuration of alkenes 1 and reductive CC-bond formation with acrylonitrile.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 1345-1351 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The Influence of Steric Effects on the Selectivity of Radical CC Bond Formation ReactionsBulky substituents R1 and R2 at radical 5 decrease the rate of addition to diethyl fumarate to a larger extent than to methyl acrylate (Table 1). The comparison with H-abstraction, which is only slightly influenced by steric effects, shows that 5e (R2 = t-C4H9) reacts at least 235 times slower with diethyl fumarate than 5a (R2 = CH3) (Table 2). Therefore, the stereoselectivity of cyclic radicals 1 (n = 1, 2) increases if the CC bond formation reaction is carried out with diethyl fumarate instead of methyl acrylate.
    Notes: Sperrige Substituenten R1 und R2 am Radikal 5 verringern die Additionsgeschwindigkeit an Fumarsäure-diethylester stärker als die Additionsgeschwindigkeit an Acrylsäure-methylester (s. Tab. 1). Der Vergleich mit dem von sterischen Effekten nur wenig beeinflußten H-Einfang zeigt, daß 5e (R2 = t-C4H9) mindestens 235mal langsamer mit Fumarsäure-diethylester reagiert als 5a (R2 = CH3) (s. Tab. 2). Deswegen steigt die Stereoselektivität der cyclischen Radikale 1 (n = 1,2) um den Faktor 5-7, wenn bei der CC-Verknüpfungsreaktion Fumarsäureester anstelle von Acrylsäureester eingesetzt wird.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 117 (1984), S. 2132-2139 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Diastereoselectivity of the CC Bond Formation Reaction of Cyclic RadicalsSolvomercuration and reductive CC bond formation reaction of cyclopentene, dihydrofuran, cyclohexene, and dihydropyran with alkenes 4 yield products 9 - 16. In these reactions the formation of trans-isomers predominantes (Tables 1 - 3). The stereoselectivity increases with decreasing reactivity of alkenes 4 and is greater with five-membered than six-membered rings. Dihydrofuran reacts with methyl acrylate to give trans-and cis-Isomers 11f and 12f in a 93:7 ratio (Table 2). In contrast, norbornene yields only the exo, cis-isomer 21.
    Notes: Solvomercurierung und anschließende reduktive CC-Verknüpfung von Cyclopenten, Dihydrofuran, Cyclohexen und Dihydropyran mit Alkenen 4 liefern die Produkte 9 - 16, wobei die Bildung der trans-Isomeren überwiegt (Tab. 1 - 3). Die Stereoselektivität steigt mit abnehmender Reaktivität der Alkene 4 sowie beim Übergang vom Sechsring zum Fünfring an. Aus Dihydrofuran und Acrylsäure-methylester entstehen die trans-und cis-Isomeren 11f und 12f im Verhältnis 93:7 (Tab. 2). Im Gegensatz dazu reagiert Norbornen ausschließlich zu dem exo, cis-Isomeren 21.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1992 (1992), S. 481-484 
    ISSN: 0170-2041
    Keywords: m-Terphenyl ; Hindrance, sterical ; Concave benzoates ; Benzoates, concave ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis and the properties of concave methyl benzoates 4 are described. The difficulties encountered in their saponification and 1H-NMR data show that these esters 4 are severely shielded. Saponification is possible via nucleophilic substitution at the methyl groups by lithium iodide in pyridines. The products are the new concave benzoic acids 5d and 5e.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1989 (1989), S. 367-374 
    ISSN: 0170-2041
    Keywords: Concave base ; 1,10-Phenanthroline ; Macrobicyclic lactam ; Template cyclization ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Konkave Reagenzien, 2. - Makrobicyclische 1,10-PhenanthrolineDrei makrobicyclische 2,9-disubstituierte 1,10-Phenanthrolin-bislactame 4 wurden mit Gesamtausbeuten bis zu 43% synthetisiert. Dabei wurden zwei Makrocyclisierungstechniken angewandt: 1) Eine Metallionen-gesteuerte Biskondensation (Templatsynthese) eines Diamins 6 mit 1,10-Phenanthrolin-2,9-dicarbaldehyd (5) führte zu neuen makrocyclischen 1,10-Phenanthrolin-Diimin-Komplexen 7 (Schiff-Basen, als Pb2⊕-Komplexe isolierbar), die durch Reduktion mit NaBH4 in die makrocyclischen Diamine 8 übergeführt werden konnten. 2) Die makrocyclischen Diamine 8 wurden mit Dicarbonsäuredichloriden 9 nach dem Verdünnungsprinzip zu den Makrobicyclen 4 umgesetzt. - Die Synthesen der Bicyclen 4, ihre Reaktionen mit Cu⊕ und die relativen Basizitäten von 4 und Vergleichsverbindungen in Ethanol werden beschrieben.
    Notes: Three macrobicyclic 2,9-disubstituted 1,10-phenanthroline-containing bislactams 4 were synthesized in overall yields of up to 43%. Two successive macrocyclization techniques were used: i) metal ion template-assisted bis-condensations of diamines 6 with 1,10-phenanthroline-2,9-dicarbaldehyde (5), leading to new macrocyclic 1,10-phenanthroline-diimine complexes 7 (Schiff bases, isolable as their Pb2⊕ complexes), which were then reduced with NaBH4 to yield the macrocyclic diamines 8, and ii) a high dilution cyclization reaction between the macrocyclic diamines 8 and diacyl dichlorides 9. - Syntheses, complexing abilities towards Cu⊕, and relative basicities of 4 and related compounds in ethanol are reported.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
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