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Mass spectra of new substituted 2-amino-4H-pyrans: a retro-Diels-Alder reaction pattern

✍ Scribed by Ana de Lucas; Javier Fernández-Gadea; Nazario Martin; Roberto Martínez; Carlos Seoane

Publisher: John Wiley and Sons
Year: 2000
Tongue: English
Weight: 54 KB
Volume: 14
Category: Article
ISSN: 0951-4198
DOI: 10.1002/1097-0231(20001015)14:19<1783::aid-rcm92>3.0.co;2-1

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✦ Synopsis

New substituted 2-amino-3-cyano-4H-pyrans have been studied by electron ionization (EI), chemical ionization (CI) and electrospray ionization (ESI) mass spectrometry. The retro-Diels-Alder reaction (RDA) is the main fragmentation pattern observed in the EI spectra forming an unsaturated ketone as the diene fragment. In contrast, a different RDA reaction takes place yielding an unsaturated amide as diene fragment together with the unsaturated ketone in the CI spectra. The MS/MS spectra obtained using an ESI source reveal that the favoured fragmentation by collision induced dissociation (CID) is the elimination of the substituent at the C4 position with formation of a stable pyrilium cation.

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