Electron impact fragmentation mechanisms of some cyclic esters with helical structures

The electron impact mass spectra of several cyclic esters with helical stru ctures have been studied, Their fragmentation pathways were proposed and co nfirmed by mass-analyzed ion kinetic energy (MIKE) and high-resolution data . In general, the dominant fragmentation pathways in the spectra of these c ompounds originate from a or-cleavage with loss of a hydrogen or methyl gro up. The difference between hydrogen and methyl group loss greatly affects t he subsequent fragmentations. Although, due to their helicity, these cyclic esters are optically active no stereo-related fragmentation pathway was ob served. Copyright (C) 2000 John Wiley & Sons, Ltd.