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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 323 (1981), S. 33-40 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: On the Reduction of 1,3-Thiazinium Salts; Synthesis of 6,6′-Bi-1,3-Thiazinyls and 6,6′-Bi-1,3-Thiazinylidenes1,3-Thiazinium perchlorates 1 are linked together in a reaction with zinc powder or at a cathode forming 6,6′-bi-1,3-thiazinyls 3. This reaction proceeds via radical intermediates 2. Evidence of the existence of the very short-lived radicals is given by means of ring-disk-voltammogrammes as well as by electrochemical luminescence excitation. The 6,6′-bi-1,3-thiazinyls 3 undergo the reverse fission at a platinum anode resulting in thiazinium salts 1, whereas the dehydrogenation by chloranile yields the violet 6,6′-bi-1,3-thiazinylidenes 6.
    Additional Material: 2 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 327 (1985), S. 523-528 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: N.M.R. Spectroscopic Z/E Configuration Determination of 1,2-Dithioethene Derivatives
    Additional Material: 2 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 328 (1986), S. 314-320 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reaction of (2-Alkoxy-vinyl)hetero-methiniminium Salts with C-Nucleophiles  -  an Approach to Functionalized Pyrylium SaltsThe O-alkylation products 2 of 2-acyl-1-chloro-enamines 1 (X = Cl) or acylketene-S, N-acetales 1 (X = SCH3) respectively react with cyanoactivated methylene compounds 3 under C,C-bond formation. The reaction products 4 have been converted into functionally substituted pyrylium salts 5 by acidic treatment. Limitations of the synthetic approach are discussed.
    Additional Material: 1 Tab.
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 325 (1983), S. 774-786 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Theoretical Investigations on the Decomposition Equilibrium of Urea in Gaseous State and Aqueous SolutionThere is empirical evidence that among the two possible decomposition equilibria of urea in the gaseous and aqueous states the desammonation process prevails. In the present work the thermodynamic and kinetic conditions of desammonation and dehydration based on intramolecular mechanisms were examined by means of quantum chemical methods. The application of MNDO method yields correct structural data, dipole moments and ionisation potentials; the solvation is taken into account using NDDO based solvation and reaction field models. Maximum deviations concerning enthalpies of formation in π-electron rich compounds reach up to 40kJ/mole. A detailed examination of the energy hyperfaces reveals that the dehydration is kinetically hindered by a significantly high activation barrier. This situation is not essentially altered by taking into account nonspecific solvent effects in aqueous solution.
    Additional Material: 2 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 334 (1992), S. 141-146 
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: On the Regio- and Stereoselectivity of Nucleophilic Thiol Additions to PolyinesNucleophilic thiophenol additions to α,ω-diphenyl polyines Ph-(C≡C)n-Ph (n = 2-4) (1-3) take a regio- and stereoselective course. The well-defined, crystalline addition products bind the phenylthio group in terminal position of the aliphatic chain, the resulting C, C-double bonds of the mono-(4, 6, 8) and bis-addition products (5, 7, 9) are (Z)-configurated, as unequivocally proved by 13C-n.m.r. analysis.
    Additional Material: 2 Tab.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 320 (1978), S. 463-472 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Pyrylium Compounds. XIV. The Light Absorption of 1,2-Benzoxalenes (Indeno[2,1-b]pyrans)The iso-π-electronic relationship between azulene A and the heterocyclic pseudoazulene B is reflected by the same dependence of the N—V1 transition from the substituents: Many examples (1-27) show that pseudo-azulenes of the 1,2-benzoxalene type (indeno[2,1-b]pyran) C undergo a bathochromic shift by alkyl substitution at C3 and C6, but an hypsochromic shift by alkyl substitution at C7. Second order substituents effect an opposite influence (examples 92-98). The conjugative effect of substituents causes a bathochromic shift in all positions (examples 49-58), which may rise to a remarkable amount with the extension of the conjugated system (examples 59-91). The relations obtained correspond to the results of quantum-chemical calculations (examples 28-48).
    Additional Material: 6 Tab.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 321 (1979), S. 274-278 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polarographic Investigations of 1,3-Thiazinthiones1,3-Thiazine-6-thiones are stepwise reduced in aprotic media to the corresponding radical anions and dianions. In the case of the 2,4-diphenyl derivative (1a) the radical anion is stable in dimethylformamide, whereas the dianion reacts further to yield the bithiazinylidene (4) among other products.The effect of substituents on the reduction potentials is discussed.
    Additional Material: 1 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 6 (1993), S. 489-493 
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Dipole moments of a series of 2,6-bis(dimethylamino) and 2,6-bis(pyrrolidino) derivatives of 4H-pyran-4-one (2), 4H-thiopyran-4-thione (3), 4H-pyran-4-thione (4) and 4H-thiopyran-4-thione (5) were determined in benzene and dioxane solutions at 25°C. High values of the dipole moments (6·44-8·44 D) and mesomeric moments originated from delocalization of the nitrogen lone pairs into the π-system of the heterocyclic moieties (1·11-3·08 D) indicate a strong polarization of the molecules 2-5 due to a tendency to stabilize pentamethinium and pyrylium (thiopyrylium) ionic structures. The MNDO-calculated electronic distribution in 2-5 compared with that for the parent 4H-pyran(thiopyran)-4-one(thione)s is in line with this conclusion.
    Additional Material: 3 Tab.
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  • 9
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Generation of N,N-Disubstituted Iminium Salts by Application of Silane Reagents(Dialkylamino)trimethylsilanes, halotrimethylsilanes and trimethylsilyl triflate proved to be superior reagents for a convenient access to the title compounds in an aprotic medium. In most cases, the co-formation of silylethers or disiloxanes acts as driving force. A comprehensive overview on this field, including the latest findings, is given and the significant mechanistic relationships are illuminated. The three component synthesis starting from carbonyl compounds (Scheme 3) and the two component synthesis (“latent” three component synthesis) starting from α-chloroethers (Schemes 16, 19) hold a central position. The latter method offers special advantage for the entrance into the multifunctional series, as shown by the first synthesis of vinylogous Viehe salts as preparatively useful C3-building blocks (Schemes 17, 22, 23). As an aim, this report should stimulate further progress in these areas.
    Additional Material: 1 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 332 (1990), S. 148-160 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: On the Existence of 2-Imino-2H-1,3-thiazinesThe title compounds 2 are readily liberated from the 2-amino-1,3-thiazinium salts 1 by treatment with bases. Their stability depends sensitively on the substituents at the imino-N. The imino-N substituted 2a-i are isolable as well-defined coloured substances. Reaction of the 2 as well 1 with nucleophilic agents affords pyrimidine-2-thiones (4, 9-11, 16-18). In these ring transformations a nucleophilic addition at ring position 6 as primary reaction step is preferred. The imino-N unsubstituted representatives display a more complicated behaviour; the highly enhanced reactivity prevents or handicaps, respectively, any isolation. As exemplified in the base-induced ring-transformation of 1 m to the pyrimidine derivative 19, these 2 are able to react as nucleophiles too, and versatile intermolecular self-reactions are increasingly favoured.
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