BECKMANN-Umlagerung und Fragmentierung; V. Teil Mechanismus der 7-Zentren-Fragmentierung von 1-Oxo-5-oximino-9-methyl-trans-decalin. Fragmentierungsreaktionen, 22. Mitteilung
✍ Scribed by C. A. Grob; H. von Tschammer
- Publisher
- John Wiley and Sons
- Year
- 1968
- Tongue
- German
- Weight
- 395 KB
- Volume
- 51
- Category
- Article
- ISSN
- 0018-019X
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✦ Synopsis
The reaction rates of heterolytic fragmentation of S-(P-toluenesulfonyloxyimino) -1-0x0-9-methyl-trans-decalin ( l ) , induced by sodium hydroxide in 80% ethanol and by sodium ethoxide in 100% cthanol, has been determined. The reaction of the oxirne tosylate 1 with sodium ethoxide is first order with respect t o both reactants. A similar base-dependence is observed in the reaction of the oxinic tosylate 1 with sodium hydroxide.
These results are explained in terms of an addition-fragmentation mechanism. This involves reversible addition of NaOH or NaOC,H, to the carbonyl group of the oxime tosylate 1 and concerted fragmentation of the addition compounds 5 a and 5 b, yielding 9-cyano-6-methyl-trans-non-5-enoic acid (4a) and the corresponding ethyl ester 4b, respectively. These reactions appear t o be the first cases of concerted and stereospecific 7-centre fragmentation.
Wie kurzlich gezeigt wurde i l j , reagiert der $-Toluolsulfonsaureester von 1-0x0-5-oximino-9-methyl-tralzs-decalin (1) in 80-proz. Athanol unter BECKMANN-Umlagerung zum Ketolactam 2 und zum Lactim-athylather 3. Mit steigenden Zusatzen von Natriumhydroxid gewinnt die konkurrierende 7-Zentren-Fragmentierung zu 6-Methyl-9-cyano-trans-non-5-ensaure (4 a) an Bedeutung und dominiert schliesslich. Natriumathylat in abs. Athanol lost eine analoge Spaltung zum Athylester von 4a, namlich 4b, aus.