B ECKMANN ‐Umlagerung und Fragmentierung. II. Teil. Versuche zur 7‐Zentren‐Fragmentierung von γ‐Aminoketoximen. Fragmentierungsreaktionen, 19. Mitteilung

The occurrence of so‐called synchronous 7 ‐centre‐fragmentation has been excluded for γ‐amino‐ketoxime derivatives NCCCCNX. Fragmentation may occur, however, by another route. Reaction rates of the p ‐toluenesulfonates of (4‐quinuclidinyl)‐methyl‐ketoxime ( 10b ) and (3β‐tropanyl)‐methyl‐ketoxime ( 14b ) in 80% ethanol and the resulting products have been determined. Whereas the latter γ‐aminoketoxime underwent quantitative B ECKMANN rearrangement to 3β‐acetylaminotropane ( 29 ), the former yielded 3% fragmentation products besides rearranged 4‐acetylamino‐quinuclidine ( 13 ). A kinetic study reveals that both 10b and 14b react via the rearranged nitrilium ions 12a and 16a , respectively. In the case of the N‐(4‐quinuclidinyl)‐acetonitrilium ion ( 12a ) 5‐centre‐fragmentation competes with hydration to the amide 13 .