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  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1991 (1991), S. 513-517 
    ISSN: 0170-2041
    Keywords: Nitrones, electron-deficient ; Oxaziridines ; Dipolarophiles ; [3+2]Photocycloadditions ; Oxazolidines ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In Order to decrease the ground state reactivity and increase their potential for [3+2] cycloadditions, cyano- and methoxy-carbonyl-substituted nitrones 1a and 1b, respectively, were prepared and irradiated in the presence of electron-rich alkenes such as 2 to afford the corresponding oxazolidines in which th oxygen atom becomes attached to the least substituted terminus of the olefin and nitrogen attaches to the more highly substituted counterpart. While the oxazolidines 12a and 12b obtained from 1b, via the intermediacy of oxaziridine(s) 15 and subsequent N—O bond scission, are isolated and characterized, the oxazolidin(s) 18 formed bny cyclization of 1a are more labile and may undergo ionization to the stabilized oxazolinium ion 19 followed by nucleophilic attack by cyanide ion with accompanying ring opening to afford 6. A sequential diradical mechanism is proposed to rationalize the formation of the observed photoproducts 5 and 6.
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 335 (1993), S. 461-464 
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Tetrazole Compounds. 6. Acylation of 1-Aryl-5-(2-dialkylamino-vinyl)-1 H-tetrazoles by Trifluoro- and Trichloroacetic Anhydrides
    Additional Material: 2 Tab.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 336 (1994), S. 79-82 
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Tetrazole Compounds. 7. New Types of Pyrazolyl- and Isoxazolyl-tetrazoles from Enamino Ketone Precursors
    Additional Material: 1 Tab.
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 332 (1990), S. 453-460 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Substituted 2-Amino-thiazoles from α-Thiocyanato-acetophenones and Dialkylaminesα-Thiocyanato-acetophenones 1 react with dialkylammonium salts of weak acids (acetates, propionates, benzoates) to give 2-dialkylamino-4-aryl-thiazoles 4. As reaction medium aliphatic alcohols (methanol, ethanol), dipolar-aprotic solvents (acetonitrile, dimethylformamide, dimethyl sulphoxide) or chlorinated hydrocarbons (methylene chloride, chloroform, carbon tetrachloride) can be used. In comparison to known methods for the preparation of the thiazoles 4 the synthesis via α-thiocyanato-acetophenones 1 has the advantage of the simpler accessible starting compounds. - I.r., u.v., n.m.r. and mass spectroscopic data of the thiazoles 4 are reported.
    Additional Material: 3 Tab.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 332 (1990), S. 977-994 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Tetrazole Compounds. 5. Synthesis and Transamination of Enamino Ketones of the Tetrazole SeriesTetrazole-5-acetaldehyde enamines 5 react with aliphatic and aromatic carboxylic acid chlorides in the presence of an auxiliary base (e.g. pyridine or triethylamine) to give tetrazolylsubstituted enamino ketones 6. The latter can be modified by acid-catalyzed transamination with secondary aliphatic amines (e.g. diethylamine, pyrrolidine, piperidine, morpholine, hexamethylene imine) yielding 5-(1-acyl-2-dialkylamino-vinyl)-1-aryl-1 H-tetrazoles 7. The analogue transamination of 6 with primary alkyl, aralkyl, and aryl amines results in corresponding secondary enamino ketones 8, which exist in solution as an equilibrium mixture of the Z and E form. Acylation of secondary tetrazole-5-acetaldehyde enamines 9 does not lead to 8, but to the isomeric N-acyl derivatives 10. - Characteristic 1H-n.m.r., u.v., and i.r. spectroscopic data of the novel products are reported.
    Additional Material: 3 Tab.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 332 (1990), S. 723-730 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Substituted N,N′-Bis(thiazol-2-yl)-diaminoalkanes from α-Thiocyanato-acetophenones and N,N′-Dialkyl-diaminoalkanesα-Thiocyanato-acetophenones 1 react with N,N′-dialkyl-diaminoalkanes 2 in the presence of an appropriate weak acid (acetic acid, propionic acid, benzoic acid) to give the hitherto unknown N,N′-dialkyl-N,N′-bis(4-aryl-thiazol-2-yl)-diaminoalkanes 3. As reaction medium aliphatic alcohols (ethanol, methanol), halogenated hydrocarbons (methylene chloride, chloroform, carbon tetrachloride) or dipolar-aprotic solvents (acetonitrile, dimethylformamide) can be used. - I.r., u.v., n.m.r. and mass spectroscopic data of the novel bisthiazoles 3 are reported.
    Additional Material: 3 Tab.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 333 (1991), S. 727-732 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Pyrylium Compounds. 46. 4-Aroyl-fluoren-9-ones by Ring Transformation of 2,4,6-Triarylpyrylium Salts with Indan-1,3-dioneThe ring transformation of 2,4,6-triarylpyrylium salts 1 with indan-1,3-dione in the presence of a condensing agent such as piperidine acetate, triethylamine/acetic acid, triethylamine or sodium acetate leads to 4-aroyl-1,3-diaryl-fluoren-9-ones 6. As reaction medium aliphatic alcohols (methanol, ethanol), dipolar aprotic solvents (acetonitrile, dimethylformamide) or chlorinated hydrocarbons (methylene chloride, chloroform) can be used. The structure of the novel compounds 6 was confirmed by spectroscopic methods as well as by independent synthesis of the fluorenone 6a.
    Additional Material: 1 Tab.
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 332 (1990), S. 540-546 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 2-Dialkylamino-thiazolin-4-ones from α-Thiocyanato-carboxylic Acid Derivativesα-Thiocyanato-acetic acid esters 1a-c or amide 1d react with dialkylamine salts of weak acids to give 2-dialkylamino-thiazolin-4-ones 2a-f. The reaction can be performed using aliphatic alcohols, dipolar aprotic solvents or halogenated hydrocarbons as reaction medium or by heating the educts at 90°C without any solvent. According to the latter method, the 5-substituted thiazolinones 2g, h are obtained from α-thiocyanatopropionic acid ethyl ester (1d) or α-thiocyanato-phenylacetic acid ethyl ester (1e) and dimethylamine acetate. - I.r., u.v. and n.m.r. data of the thiazolinones 2 are reported.
    Additional Material: 2 Tab.
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 333 (1991), S. 717-726 
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Pyrylium Compounds. 45. 4-Aroyl-fluorenes from 2,4,6-Triaryl-pyrylium Salts and Indan-1-one via 2-(5-Oxo-pent-2-en-1-yliden)-indan-1-ones2,4,6-Triarylpyrylium salts 1 react with indan-1-one in the presence of an appropriate buffer system (e.g. piperidine acetate, triethylamine/acetic acid, triethylamine or sodium acetate) to yield the 2-(1,3,5-triaryl-5-oxo-pent-2-en-1-yliden)-indan-1-ones 2. For the reaction medium aliphatic alcohols (methanol, ethanol), dipolar aprotic solvents (acetonitrile) or chlorinated hydrocarbons (methylene chloride, chloroform, carbon tetrachloride) can be used. On treating 2 with sodium methanolate in methanol, a cyclization reaction occurs giving rise to the 4-aroyl-1,3-diaryl-fluorenes 3. As by-products 1,3-diaryl-fluorenes 8 (e.g. 1,3-diphenyl-fluorene) are formed. - I.r., n.m.r. and u.v. spectroscopic data of the novel compounds 2 and 3 are reported.
    Additional Material: 3 Tab.
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