Fragmentierung von α‐Aminoketoximen. IV. Teil Der Einfluss sterischer. Faktoren Fragmentierungsreaktion, 17. Mitteilung

(N‐Methyl‐2‐piperidyl)phenyl ketoxime acetate( 10b ) and (N‐methyl‐2‐pyrrolidinyl)‐phenyl ketoxime acetate ( 13b ) undergo quantitative fragmentation in 80% ethanol to yield benzonitrile and the cyclic imonium salts 11 and 14 . Their reaction rates are approx. 10 7 and 10 8 , respectively, as high as those calculated for the homomorphous compounds, viz. 2‐methylcyclohexylphenyl ketoxime acetate ( 12b ) and 2‐methylcyclopentylphenyl ketoxime acetate ( 15b ), which undergo quantitative Beckmann rearrangement. Synchronous fragmentation therefore provides a very large driving force for ionisation, even when the stereo‐electronically suitable conformation is not the prevalent one, as with 10b .