Die Massenspektren von dreikernigen pflanzlichen Phlorogluciden

Abstract

Abstract The mass spectra of four naturally occurring tricyclic phloroglucinol derivatives are presented. Molecular ion peaks are visible in all cases and most of the fragments can be understood by assuming that a cleavage of a methylene bridge occurs with the transfer of a hydrogen atom from a hydroxyl group, located ortho to the bridge, to the adjacent ring. This fragmentation pattern is analogous to that found earlier in bicyclic phloroglucinol derivatives [2]. Some other important peaks can only be rationalized by assuming that two types of thermal rottlerone rearrangements [3]‐[5] are occurring simultaneously: 1. Disproportionation of terminal intermolecular exchange; 2. Elimination of the middle ring, thus forming a bicyclic compound from two terminal rings.