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Electron Ionization Induced Fragmentation of some 3-Aroylamino-5-Methyl-1,2,4- Oxadiazoles and 3-Acetylamino-5-Aryl-1,2,4-Oxadiazoles

[ Vol. 21 , Issue. 21 ]

Author(s):

Leopoldo Ceraulo, David Bongiorno, Serena Indelicato*, Carla Boga, Giuseppe Avellone, Vita Di Stefano, Vincenzo Frenna, Luca Zuppiroli and Domenico Spinelli*   Pages 2207 - 2215 ( 9 )

Abstract:


Background and Objectives: 1,2,4-Oxadiazoles show a high reactivity and represent starting compounds for the synthesis of several other heterocycles. Some their derivatives can give the so called Boulton- Katritzky Reactions (BKR) which opens the way to the synthesis of several azoles. For this reason we have registered the mass spectra of several 3-aroylamino-5-methyl-1,2,4-oxadiazoles and 3-acetylamino-5-aryl- 1,2,4-oxadiazoles.

Methods and Results: Thus, studying the mass spectra of the isomeric couple 3-benzoylamino-5-methyl-1,2,4- oxadiazole (1A) and 3-acetylamino-5-phenyl-1,2,4-oxadiazoles (1B) we have observed that MIKE and CID MIKE spectra of their molecular ions and of the [M – CH2CO]+. evidence that several fragmentation processes arise from common structure(s).

Conclusions: These findings lead to suggest that the BKR could occur also under electron ionization. In order to evidence possible substituent effects the EI-MS spectra of a large series of 3-aroylamino-5-methyl-1,2,4- oxadiazoles (2A-19A) and of the corresponding 3-acetylamino-5-aryl-1,2,4-oxadiazoles (2B-19B) have been examined.

Keywords:

Mass spectrometry, Fragmentation mechanisms, EI induced rearrangements, boulton-Katritzky reactions (BKR), 3-acylamino- 1, 2, 4-oxadiazoles.

Affiliation:

Department STEBICEF, University of Palermo, Ed. 16 Viale delle Scienze 90128 & via Archirafi 32, 90123, Palermo, Department STEBICEF, University of Palermo, Ed. 16 Viale delle Scienze 90128 & via Archirafi 32, 90123, Palermo, Department DISTEM, University of Palermo, via Archirafi 28, 90123, Palermo, Department of Industrial Chemistry ‘Toso Montanari’ Alma Mater Studiorum - University of Bologna, Viale del Risorgimento 4, 40136 Bologna, Department STEBICEF, University of Palermo, Ed. 16 Viale delle Scienze 90128 & via Archirafi 32, 90123, Palermo, Department STEBICEF, University of Palermo, Ed. 16 Viale delle Scienze 90128 & via Archirafi 32, 90123, Palermo, Department STEBICEF, University of Palermo, Ed. 16 Viale delle Scienze 90128 & via Archirafi 32, 90123, Palermo, Department of Industrial Chemistry ‘Toso Montanari’ Alma Mater Studiorum - University of Bologna, Viale del Risorgimento 4, 40136 Bologna, Department of Chemistry, ‘Giacomo Ciamician’ Alma Mater Studiorum - University of Bologna, via Selmi 2, 40126 Bologna

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