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Beckmann‐Umlagerung und Fragmentierung, IV. Teil. 5‐ und 7‐Zentren‐Fragmentierung von γ‐Keto‐ketoximen: Fragmentierungsreaktionen, 21. Mitteilung
Author(s) -
Eisele W.,
Grob C. A.,
Renk E.,
Von Tschammer H.
Publication year - 1968
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.660510421
Subject(s) - chemistry , beckmann rearrangement , nucleophile , sodium ethoxide , fragmentation (computing) , medicinal chemistry , ketone , stereochemistry , ethanol , organic chemistry , oxime , computer science , operating system , catalysis
A heterolytic 7‐centre fragmentation reaction of the type a‐b‐c‐d‐e‐f‐X → a b + c = d + e = f + X has been demonstrated for the first time utilizing γ‐keto‐ketoximes. This system may also undergo a novel 5‐centre fragmentation. With sodium hydroxide in aqueous ethanol and with sodium ethoxide in ethanol the p ‐toluene‐sulfonate of 1‐oxo‐9‐methyl‐5‐oximino‐ trans ‐decalin (7b) is converted quantitatively into 9‐cyano‐6‐methyl‐non‐5‐enoic acid (10b) and the corresponding ethyl ester, respectively. With lower concentrations of nucleophile normal Beckmann rearrangement to the lactam 13a and the lactimether 19b predominates. In the case of the p ‐toluenesulfonate of the 9‐nor‐derivative 7a a base‐induced 5‐centre fragmentation reaction to the α,β‐unsaturated ketone 12 competes with 7‐centre fragmentation to 9‐cyano‐non‐5‐enoic acid (10a), strong bases favouring the former reaction. In the absence of strong bases of nucleophiles Beckmann rearrangement again dominates.