Mass Spectrometry in Structural and Stereochemical Problems. CCXVII. Electron Impact Promoted Fragmentation of O-Methyl Oximes of some α,β-Unsaturated Ketones and Methyl Substituted Cyclohexanones

Abstract

Deuterium labeling and high resolution mass spectrometry have been utilized to delineate the modes of mass spectrometric fragmentation of O-methyl oximes of α,β-unsaturated ketones and methyl substituted cyclohexanones. α,β-Unsaturated ketone and 2- and 4-methylcyclohexanone O-methyl oxime ether derivatives fragment upon electron impact in a manner reminiscent of the carbonyl derivatives from which they were prepared. However, several fragmentation sequences characteristic of the O-methyl oxime ether group were observed.