3-Aroyl-5-hydroxyflavones: synthesis and mechanistic studies by mass spectrometry

✍ Scribed by Cardoso, Ana M.; Silva, Artur M. S.; Barros, Cristina M. F.; Almeida, Lúcia M. P. M.; Ferrer-Correia, A. J.; Cavaleiro, José A. S.

• Book ID: 102647067
• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 553 KB
• Volume: 32
• Category: Article
• ISSN: 1076-5174
• DOI: 10.1002/(sici)1096-9888(199709)32:9<930::aid-jms549>3.0.co;2-e

✦ Synopsis

The synthesis and mass spectra of three 3-aroyl-5-hydroxyÑavones are reported. The interpretation of the mechanistic pathways for the fragmentation of the metastable molecular ions of these compounds was achieved through the analysis of their mass-analysed ion kinetic energy (MIKE) spectra and of the B2/E spectra of a few fragment ions. Labelling of the hydroxyl proton with deuterium and the analysis of the MIKE spectra of a model compound with chlorine atoms in the 2º,6º-and 2/,6/-positions led to a mechanism for the losses of and which OH~HCOĩ nvolves hydrogen migration from the 2/-or 6/-position to the 4-carbonyl oxygen atom. A mechanism for the loss of a neutral molecule of anisole from the molecular ion of the 3-aroyl-5-hydroxyÑavone with a methoxyl group in the 4º-and 4/-positions is also suggested. For the Ñavones with hydrogen or chlorine substituents at these positions, loss of a phenyl (or chlorophenyl) radical occurs instead.