Mass Spectrometric Studies. XIII. Spirocyclic Glycidic Esters

Abstract

The mass spectra of a series of spirocyclic glycidic esters derived from cyclo-butanones, -pentanones, -hexanones, -heptanones and -octanones show the following characteristic fragmentations: (i) a rearrangement involving migration of the ester alkoxy group to the ring junction, followed by elision of the group COCR=O (R = H or Me), and (ii) loss of the alkoxycarbonyl group by α-fission, followed by ring-contraction and loss of the elements of acetaldehyde. The major fragmentations are supported by deuterium-labelling experiments, and a number of minor decompositions are described.