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  • 1
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 5-Ring-Cycloamidines - Deeply Coloured Heterocycles with Unusual Properties. I. Synthesis and Spectral FeaturesThe cycloacylation reaction of benzamidines with bis-imidoylchlorides 1 derived from oxalic acid was investigated. For example, treatment of benzamidine with 1 gives the new 4H-imidazoles (3a-l) in yields up to 92%. Because of rapid H-transfer processes in solution, the NMR-spectra of 3a-l show only a single signal set. Apart from prototropism, 3c shows interesting properties as an amphoteric heterocycle. The protonation of 3c is accompanied by a change of color from orange to blue. Probably, protonation takes place on the exocyclic imino nitrogen to give a cyanine type chromophor. The resulting cation can also be regarded as an antiaromatic 1,3-diazacyclopentadienylium system. In order to investigate the influence of exocyclic substituents at nitrogen on the UV/VIS absorption, compounds 3d-h were synthesized. Whereas electron withdrawing groups cause hypsochromic shifts of the first UV/VIS absorption band, the dimethylamino group shifts this band bathochromically as exemplified by 3e. This novel cycloamidine shows strong acidochromism with bathochromic shifts of more than Δλmax = 150 nm.
    Additional Material: 2 Tab.
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 337 (1995), S. 143-152 
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: On the Aminolysis of Bis-Imidoylchlorides of Oxalic Acid. Part I. Reaction with Aromatic and Aliphatic AminesThe reaction between bis-imidoylchlorides 2 derived from oxalic acid and several aromatic and aliphatic amines was investigated. While primary aromatic amines need a thermical activation by refluxing, primary aliphatic amines give mainly at room temperature the amidines 3 in moderatly up to good yields.Proceeding from enantiomeric pure amines e.g. (R)- or (S)-1-phenethylamine the new homochiral oxalic amidines 3y and 3z with C2-symmetry were obtained. Several secondary amines react with the bis-imidoylchloride 2a to give via intramolecular cycloacylation derivatives of isatine. The new synthesized amidines 3 perform systems with a strong molecular dynamic like prototropie and E/Z-interconversion. All new compounds described were characterized by elemental analysis and spectroscopic methods.
    Additional Material: 2 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 339 (1997), S. 735-741 
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 5-Ring-Cycloamidines - Deeply Colored Heterocycles with Unusual Properties. II. Molecular- and Electronic StructureThe crystal and molecular structure of two N,N′-aryl-5-amino-imidazole-4-imides were detected by X-ray analysis. The structural parameters are discussed in conjunction with theoretical data obtained by density functional and ab initio quantum theory. The interpretation of the molecular structures derived from the X-ray diffraction study is made more difficult by statistic disorder or by enclosure of water in the crystal. The theory predicts a planar 5-amino-imidazole-4-imide parent structure with an energy barrier to H-transfer of about 25 kcal/mol (DFT RB3LYP/6-311+G** and ab initio G2(MP2) calculations). The CC bond of the five-membered ring is exceedingly long. CC-bond length elongation is also reported for oxalbisamidine. The structure of the parent compound is discussed in terms of polymethinic and antiaromatic substructures. Weinholds's Natural Bond Orbital (NBO) scheme and Natural Resonance Theory (NRT) as well as Schleyer's criterion of the Nucleus Independent Chemical Shift (NICS) is consulted to reveal the very nature of the unique bond system.
    Additional Material: 2 Tab.
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1995 (1995), S. 199-201 
    ISSN: 0947-3440
    Keywords: Macrocyclic lactams ; Oxalamides ; Atropisomeric diamines ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An Unexpected Reaction between Oxalyl Chloride and Atropisomeric DiaminesChiral diamines like (S)-1,1′-binaphthalene-2,2′-diamine (3a) were acylated by oxalyl chloride to yield mainly a macrocyclic lactame 5, whereas the eight-membered oxamide 4 was formed only in small quantity.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 337 (1995), S. 38-42 
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Aryl-(4-arylimino-4H-pyrido[1,2-a]pyrazine-3-yl)amines-Synthesis, Complex Formation with Molybdenum(0) and OxygenationThe synthesis of p-tolyl(4-p-tolylimino-4H-pyrido [1,2-a]pyrazine-3-yl)amine 8 (TTPPA) is achieved by the reaction of 2-pyridylmethylamine with oxalic acid bis(p-tolylimidoyl)chloride. The ion-pair [Na(THF)3][(TTPPAH)Mo(CO)4] 4 is obtained by the reaction of the NH-acidic compound 8 with sodium bis(trimethylsilyl)amide and (nor)Mo(CO)4 (nor = norbornadiene) dissolved in THF. The bidentate ligand anion TTPPA-H is related to the 1,4-diazadienes, but its n-donor effect is dominating. Its trans-influence results in different Mo-CO-bond lengths of 4 : 1.901 and 1.951 Å (trans-positions); 2.003 and 2.031 Å (cis-positions). In the cationic part of 4 the sodium is five-coordinate (distorted tetragonal pyramidal structure). Donor atoms are the three THF, N3 of TTPPA-H, and the oxygen atom of one CO of the moiety Mo(CO)4.8 is oxygenated by hydrogen peroxide or by dioxygen on heating. In the course of a ring transformation of the 6-membered pyrazine to the 5-membered imidazole cycle 3-p-tolyl-5-p-tolylimino-2-pyridine-2-yl-2,3-dihydro-imidazol-4-one 9 is formed. In THF two isomers 9 and 9a are observed in a molar ratio of about 1:1.4 and 9 have been characterized by single crystal x-ray diffraction.
    Additional Material: 3 Ill.
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  • 6
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Bicyclic Oxalic Amidines as Building Blocks for Highly Substituted 2,2′-Bipyridines and Benzene DerivativesThe bis-imidoylchlorides 1 derived from oxalic acid exhibit a high regio- and chemoselectivity. As in the case of 2-picolylamine 2 the acylation with oxalyl chloride furnished the expected open chained oxalic diamides 3a while the imidoylchlorides 1 yield exclusively the new pyrido[1,2-a]-pyrazines 4. These heterocycles represent readily crystallisable and orange-red coloured compounds with a mesomeric dipolar aromatic substructure. The synthetic value of 4 is based on their easy transformation into highly substituted arenes and hetarenes. Thus, electron deficient dienophiles as dimethyl acetylenedicarboxylate lead to the bipyridines 6 via Hetero-Diels-Alder-Reaction and subsequent 1,5-hydrogen shift. In a complex reaction the derivatives of maleic acid 7a-c yield the bipyridines of type 9 while the new hexasubstituted arenes 10 can be isolated under anaerobic conditions and with an excess of dienophilic component. A x-ray structural determination of 10b shows an alternation of bond lenghts in the benzene ring. This can be considered as a distinct disturbance of aromaticity caused by the arrangement of substituents.
    Additional Material: 3 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1997 (1997), S. 2553-2561 
    ISSN: 0947-3440
    Keywords: Ambident dianions ; Nitrogen heterocycles ; Tautomerism ; Spiro compounds ; Radialenes ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A novel strategy for the synthesis of nitrogen-rich heterocycles by regioselective C,N-cyclization of ambident dianions with oxalimidoyl dichlorides is reported. One-pot reactions provide γ-iminotetramic acid amides 1, radialenes 2 and tetraimino-diazaspiro[4.4]nonenones 3. Chemical properties and structural features of the new heterocyclic systems, including the tautomerism of 2, were investigated.
    Additional Material: 3 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 337 (1995), S. 508-515 
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: On the Aminolysis of Bis-Imidoylchlorides of Oxalic Acid. II. Reaction with Aliphatic Diamines and AminoalcoholsThe aminolysis of bis-imidoylchloride 1 derived from oxalic acid with several diamines and aminoalcohols was investigated. At room temperature diamines 2 as well as aminoalcohols 7 give mainly the cyclic amidines 3 and mixed amidine-imidates 8 in moderately up to good yields. While cis-1,2-diaminocyclohexane yields at room temperature the bicyclic amidine 3a, the trans isomer reacts to 3b only when heated for several hours. Depending on the conditions, the racemic 1,2-diaminopropane 2h gives derivatives of pyrazine 3h or the open-chain amidine 5 resulting from an oxidative aromatization and subsequent hydrolysis. Histamine 2i and 1,8-diamino-3,6-dioxaoctane 2p react selectively with 1 to seven- respectively twelve-membered heterocycles 3i and 3p. The mixed aliphatic and aromatic diamines 2n, o show an anomalous behaviour leading to 2,2′-bis-chinazolines 3n, o.In comparison with acyclic oxalic amidines the new cyclic derivatives show less molecular dynamic in their nmr spectra. In some cases, a s-trans-arrangement of the amidine substructure was observed.
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  • 9
    ISSN: 0947-3440
    Keywords: Carbenoids ; Imidoyl chlorides ; Oxalic amidines ; Tetraazafulvalenes ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cycloacylation of formamidine with bisimidoyl chlorides of oxalic acid yields the new 1,4,5,8-tetraazafulvalenes 4 via dimerization of carbenoid intermediates. The high symmetry of the stable heterofulvalenes as well as their dye character is confirmed by NMR and UV/Vis spectral data. Whereas methylation of these substrates leads to a mixture of diastereomeric tetramethyl derivatives 9a, b, cyclization with thiophosgene or triethyl orthoformate gives mainly the fused-ring derivatives of 2H-imidazole 10 and 12a, b, respectively. In the case of 12a, the X-ray crystal structure reveals the approximately ideal planarity of the central tetraazafulvalene subunit.
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