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  • 1
    ISSN: 1434-4475
    Keywords: Methyl N-acyl-N-(β-benzoylethyl)-glycinates ; Methyl N-acyl-3-hydroxy-3-phenyl-prolinates ; Photocyclization ; Barrier of amide rotation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The rate of the diastereoselective generation of methyl 3r,2t-N-acyl-3-hydroxy-3-phenyl-prolinates5 from n,π*-excited methyl N-acyl-N-(β-benzoylethyl)-glycinates4 depends on the height of the barrier ΔG c ≠ of amide rotation in the educts. Exclusively that rotamer cyclizes, which in the excited state is favoured sterically and by assistance of the amide or ester group for the transfer of the δ-H radical. The progress of the proline formation is determined by the rate of reproducing the favoured rotamer by the isomerization of the unfavoured.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Monatshefte für Chemie 119 (1988), S. 1405-1414 
    ISSN: 1434-4475
    Keywords: Isoxazolium salts ; N-Aroyl-N-methyl-benzoylacetamides ; Quinazoline-2,4-diones ; 2-Benzoylmethylene-quinazolin-5-ones ; Pyrrolo[1,2-a]quinazolin-5-ones ; Knorr reaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Refluxing of ethanol-acetic acid solutions of N-aroyl-N-methyl-benzoylacetamides3 causes elimination of acetophenone and generation of N(1)-substituted N(3)-methyl-1H,3H-quinazoline-2,4-diones5. In contrast, at room temperature in acetanhydride3 eliminate water yielding 2-benzoylmethylene-quinazolinones4, which at 60 °C cyclize to pyrrolo[1,2-a] quinazolin-5-ones6. The transformation4 →6 may be explained in terms of a “normal”Knorr reaction. A “anomalous”Knorr reaction was observed in the case of the more rigid4 d leading to a mixture of diasteromere7 d cis and7 d trans in kinetically controlled reaction. Favoured by intramolecular hydrogen bonding7 d cis converts to the thermodynamically more stable6 d by warming of the ethanolic solution for 3 hours.
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  • 3
    ISSN: 1434-4475
    Keywords: [2+2]-Photocycloaddition ; 2-Acetyl-5,5-dimethyl-1,3-cyclohexanedione ; 3-Acetyl-1,5,5-trimethyl-2,4-pyrrolidinedione ; 2-(2′-Acetyl-cyclohexyl)-5,5-dimethyl-1,3-cyclohexanedione ; 3-(2′-Acetyl-cyclohexyl)-1,5,5-trimethyl-2,4-pyrrolidinedione
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Irradiation of solutions of excess cyclohexene and 2-acetyl-5,5-dimethyl-1,3-cyclohexanedione (1), and 3-acetyl-1,5,5-trimethyl-2,4-pyrrolidinedione (4) results mainly in the formation of 1,5-diones2 and5. These originate from intermediate cycloadducts of cyclohexene and theexo-enols of the cyclic 1,3-diketones. The yields decrease with increasing polarity of the solvent. In solution2 and5 are in equilibrium with the cyclic hemiacetales3 and6.
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  • 4
    ISSN: 1434-4475
    Keywords: 2-[2-(Hetarylidene)ethylidene]-1,3-dicarbonyl compounds ; 2-(1,2-Dimethyl-4(1H)quinolylidene)-1,3-dicarbonyl compounds ; 6,12-Methano-dibenz[d,g][1,3]oxazocinones ; X-ray analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Aufgrund ihres Enamincharakters reagieren die Methylen-N-heterocyclen1–5 mit cyclischen 2-Ethoxymethylen-1,3-dicarbonylverbindungen6 zu den 2-[2-(Hetaryliden)ethyliden]-1,3-dicarbonylverbindungen7–14. Das Ergebnis der Reaktionen zwischen 1,2-Dihydro-1-methyl-2-methylen-chinolin (1a) und cyclischen 1,3-Dicarbonylverbindungen hängt von der Natur der zwischenzeitlich entstehenden DihydroverbindungenA/B ab. Die Intermediat-KetoneA gehen durch Dehydrierung während der Reaktion in die 2-(1,2-Dimethyl-4(1H)chinolyliden)-1,3-dicarbonylverbindungen17–21 über. Die Intermediat-EnoleB mit sechsgliedrigem Dicarbonylring bilden in intramolekularer Reaktion die 6,12-Methano-dibenz[d,g][1,3]oxazocinone22–25, deren Struktur am Beispiel der Verbindung23 durch1H-NMR sowie durch Röntgenkristallstrukturanalyse bewiesen wird.
    Notes: Summary The enamine-type methylene-N-heterocycles1–5 react with cyclic 2-ethoxymethylene-1,3-dicarbonyl compounds6 to give 2-[2-(hetarylidene)ethylidene]-1,3-dicarbonyl compounds7–14. The result of the reactions between 1,2-dihydro-1-methyl-2-methylene-quinoline (1a) and cyclic 1,3-dicarbonyl compounds depends on the nature of the dihydro intermediatesA/B. Dehydrogenation of keton intermediatesA results in 2-(1,2-dimethyl-4(1H)-quinolylidene)-1,3-dicarbonyl compounds17–21. Enol intermediatesB with 6-membered dicarbonyl ring form 6,12-methano-dibenz-[d,g][1,3]oxazocinones22–25.1H NMR spectra and X-ray structure analysis prove the structure of23.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 335 (1993), S. 42-46 
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Photochemistry of Aminoketones. XV. Photochemical Acyl Migration in N-Tosyl-β-aminovinyl-phenyl-ketonesN-Tosyl-β-aminovinyl-phenyl-ketones 1a - i are prepared in good yields from β-chlorovinyl- phenyl-ketones by reaction with the sodium salts of tosyl amides in dry DMF at room temperature. In contrast to the relatively photostable N, N-dialkyl-β-aminovinyl-aryl-ketones the electronically excited 1 give irreversible chemical reactions within a few minutes. Among other not identified photoproducts the α-tosyl-β-aminovinyl-phenyl-ketones 2 were found. From the experimental results it is evident that the migration of the tosyl group prefers a radical-type two step reaction through an intermediate X/Y of a (1,5)-N→O-tosylrearrangement.
    Additional Material: 2 Tab.
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 101 (1968), S. 3963-3968 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Phosphorigsäure-triäthylester (1) bildet mit 1-Chlor-2-hydroxy-3-alkoxy-propanen 2 bei 120-150° in merklichem Ausmaß die entsprechenden β-Hydroxy-phosphonsäureester 3. Oberhalb 150° treten bevorzugt die Folgeprodukte einer Umesterung 1→4 auf. Neben höhermolekularen Verbindungen, die aus intermolekularen Reaktionen hervorgehen, entstehen u.a. cyclische Phosphonsäureester, so z.B. 1.3.2-Dioxaphospholane 8 und β-Phostone 11.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1992 (1992), S. 813-816 
    ISSN: 0170-2041
    Keywords: Pyridines ; (4-Pyridyl)acetyl building units ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 5-(4-Pyridyl)-1,3-dioxan-4,6-diones  -  Preparation and Reactions with O-, N- and C-NucleophilesThe reaction between alkyl chloroformates, pyridine and 1,3-dioxane-4,6-diones yields 5-[1-alkoxycarbonyl-4(1H)-pyridylidene]-1,3-dioxane-4,6-diones 3 via the dihydro intermediates 2. The compounds 3 transfer the alkoxycarbonyl group readily to O-, N- and C-nucleophiles. Hydrolysis of 3a-e affords 2,2-dimethyl-5-(4-pyridyl)-1,3-dioxane-4,6-dione (4a), which in solution exists in the NH tautomeric form. Nucleophilic reagents attack 4a at one of the carbonyl groups to yield derivatives of (4-pyridyl)acetic acid. These reactions admit a convenient access to a number of 4-pyridyl-substituted heterocycles.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 92 (1959), S. 2756-2760 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Es werden geeignete Reaktionsbedingungen für die Umsetzung von Triphenylphosphin mit verschiedenen Alkyl- und Aralkylhalogeniden angegeben. Diese gestatten u.a. die bequeme und getrennte Darstellung mono- und bifunktioneller Phosphoniumsalze aus Di-Halogenverbindungen.
    Additional Material: 2 Tab.
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 92 (1959), S. 2944-2952 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Triphenyl-benzyl-phosphoniumsalze lassen sich in basischem Milieu über die Zwischenstufe der Phosphor-ylene mit geeigneten aromatischen Aldehyden zu stilbenartigen zwei- oder mehrkernigen Verbindungen umsetzen. Es wird eine Abschätzung der Reaktionsbedingungen gegeben und die Möglichkeit einer schrittweisen Reaktion zwischen ω.ω′-Dihalogenverbindungen und zwei Äquivalenten Aldehyd behandelt.
    Additional Material: 2 Tab.
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 336 (1994), S. 169-171 
    ISSN: 0941-1216
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Photochemistry of Aminoketones. XVI. About the Influence of N-Substitutents on Photochemical Behaviour of Enaminoketones
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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