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  • Organic Chemistry  (12)
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  • 11
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 73 (1990), S. 896-901 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: (±)-Muscone ((±)-1) has been synthesised in three steps from 2-(2′-methylprop-2′-enyl)cyclododecan-1-one (2). The synthesis involves two key transformations: a Lewis-acid-mediated intramolecular ene reaction (2→3) and the β-cleavage of the bicyclic potassium alkoxide 3a′ to the macrocyclic enone (Z)-11.
    Type of Medium: Electronic Resource
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  • 12
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ring Enlargements and Ring Contractions in the Reaction of 1, 3-Oxazolidine-2, 4-diones and l, 3-Thiazolidine-2, 4-dione with 3-Amino-2H-azirinesThe reaction of 3-amino-2H-azirines 1 and 1, 3-oxazolidine-2, 4-diones 2 in MeCN at room temperature leads to 3, 4-dihydro-3-(2-hydroxyacetyl)-2H-imidazol-2-ones 3 in good yield (Scheme 2, Table 1). A reaction mechanism proceeding via ring enlargement of the bicyclic zwitterion A to give B, followed by transannular ring contraction to C, is proposed for the formation of 3. This mechanism is in accordance with the result of the reaction of 2a and the 15N-labelled 1a*: in the isolated product 3a*, only N(3) is labelled (Scheme 1). The analogous reaction of 1 and 1, 3-thiazolidine-2, 4-dione (5) is more complex (Schemes 4 and 5, Table 2). Besides the expected 3, 4-dihydro-3-(2-mercaptoacetyl)-2H-imidazol-2-ones 7, 5-amino-3, 4-dihydro-2H-imidazol-2-ones of type 8 and/or N-(1, 4-thiazin-2-ylidene)ureas 9 are formed. In the case of 2-(dimethylamino)-1-azaspiro[2. 3]hex-1-ene (1d), the postulated eight-membered intermediate 6d could be isolated. Its structure as well as that of 9f has been determined by X-ray structure analysis. A reaction mechanism for the formation of the 1, 4-thiazine derivatives of type 9 is proposed in Scheme 6.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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