5-Hydroxy-2-isopropyl-7-methoxychromone (1d), a chromone constituent isolated from the aerial parts of Baeckea frutescens, and four analogues (1a-c and 1e), all of which exhibit toxicity to the brine shrimp Artemia salina, have been prepared from 2',4',6'-trihydroxyacetophenone. High-resolution mass spectrometric analysis has permitted elucidation of the fragmentation patterns exhibited by these systems following electron-impact ionization.