- 3-Aroyl-5-hydroxyflavones: Synthesis and mechanistic studies by mass spectrometry
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The synthesis and mass spectra of three 3-aroyl-5-hydroxflavones 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 2',6'- and 2',6'-positions led to a mechanism for the losses of OH. and HCO. which involves hydrogen migration from the 2'- or 6'-position to the 6-carbonyl oxygen atom. A mechanism for the loss of a neutral molecule of anisole from the molecular ion of the 3-aroyl-5-hydroxyflavone with a methoxyl group in the 4'- and 4'-positions is also suggested. For the flavones with hydrogen or chlorine substituents at these positions, loss of a phenyl (or chlorophenyl) radical occurs instead.
- Cardoso, Ana M.,Silva, Artur M. S.,Barros, Cristina M. F.,Almeida, Lucia M. P. M.,Ferrer-Correia,Cavaleiro, Jose A. S.
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- 3-Aroyl-5-hydroxyflavones: Synthesis and transformation into aroylpyrazoles
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Treatment of 3-aroyl-5-benzyloxyflavones 4a-e with hydrazine afforded 3,5-diaryl-4-(2-benzyloxy-6-hydroxybenzoyl)pyrazoles 5a-e, together with 4-aroyl-5-aryl-3-(2-benzyloxy-6- hydroxyphenyl)pyrazoles 6a-e as minor products. The structures of all new compounds have been established by extensive NMR studies and the reaction mechanisms are discussed. Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002.
- Pinto, Diana C. G. A.,Silva, Artur M. S.,Almeida, Lucia M. P. M.,Cavaleiro, Jose A. S.,Elguero, Jose
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p. 3807 - 3815
(2007/10/03)
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