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  • 1
    Electronic Resource
    Electronic Resource
    Reactions of Thiobenzophenone S-Methylide with Thiocarbonyl Compounds (2000)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 1695-1702 
    Details
    ISSN: 1434-193X
    Keywords: Thiocarbonyl ylides ; Cycloadditions ; Dithiolanes ; Sulfur heterocycles ; Thioketones ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---2,5-Dihydro-2,2-diphenyl-1,3,4-thiadiazole (4) eliminates N2 at -45 °C and generates thiobenzophenone S-methylide (5), which is intercepted by dipolarophiles. The 1,3-cycloadditions of 5 with thiones (aromatic and aliphatic thioketones, dithioesters, trithiocarbonate) furnish 1,3-dithiolanes 7, in which the substituents, even voluminous ones, appear in the proximal 4- and 5-positions. The reaction of 5 with adamantanethione furnishes 7h and 4,4,5,5-tetraphenyl-1,3-dithiolane (7a) in a ratio of 4:1; a methylene transfer is involved, and the mechanistic pathways are discussed. The cycloadduct 7f originating from 5 and diphenyl trithiocarbonate undergoes an isomerization which consists of ionization and ring-opening leading to a ketene dithioacetal structure.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    1,3-Dipolar Cycloadditions, 96. - Cycloadditions of Alicyclic Thione S-Oxides with Alicyclic ThionesThis paper is dedicated to Siegfried Hünig, Würzburg, on the occasion of his 75th birthday. (1997)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1997 (1997), S. 179-185 
    Details
    ISSN: 0947-3440
    Keywords: 1,3-Cycloadditions ; Sulfines (thione S-oxides) ; 1,2,4-Oxadithiolanes ; Calculation of TS ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Thione S-oxides (sulfines) harbor the allyl anion MO of 1,3-dipoles, but fail to undergo 1,3-cycloadditions to the usual dipolarophiles with a CC multiple bond. Thioketones stand the test as superdipolarophiles. The thione S-oxides 3 and 9 combined with the thioketones 5 and 7 at 80-100°C, furnishing spiro-1,2,4-oxadithiolanes in high yields despite steric hindrance. The structures of the cycloadducts were clarified by their spectra and an X-ray analysis of 11. Becke3LYP/6-31G* calculations of transition structures and products for the cycloadditions of thioformaldehyde S-oxide to thioformaldehyde support the observed regiochemistry. The activation energy amounts to 3.9 kcal mol-1, in contrast to EA = 17.4 kcal mol-1 for the corresponding addition to ethylene. The transition structures are in accordance with concerted cycloadditions.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199719970126
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  • 3
    Electronic Resource
    Electronic Resource
    1,3-Dipolar Cycloadditions, 97. - Some Cycloadditions of Aromatic Thione S-OxidesDedicated to Professor Hans Suschitzky, Salford, on the occasion of his 80th birthday. (1997)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1997 (1997), S. 187-192 
    Details
    ISSN: 0947-3440
    Keywords: 1,2,4-Oxadithiolanes ; 1,2,4-Trithiolanes ; Thione S-oxides (sulfines) ; Thione S-sulfides (thiosulfines) ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Surprisingly, thiobenzophenone S-oxide (5) and thione 6 afforded the spiro-1,2,4-trithiolane 7 (86%) instead of the expected spiro-1,2,4-oxadithiolane 16. Structure 7 was established via spectra, single-crystal X-ray analysis, and an independent synthesis from thiobenzophenone S-sulfide (15) and 6. On accepting the formation of 16 by 1,3-cycloaddition as a first step, we reduced the mechanistic problem to the conversion 16 + 6 → 15 + dione 8; three conceivable pathways are discussed. Thiofluorenone S-oxide (25) combines with 6 to the trithiolane 27 in low yield; the spontaneous conversion of 25 to 9,9′-bifluorenylidene (26) takes precedence. No 1,3-cycloaddition is involved in the 1:1 reaction of 5 with (E)-cyclooctene (28); 5 combines as a hetero-1,3-diene with 28 to a Diels-Alder type adduct 30.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199719970127
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