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

, : Mass spectra of new substituted 2-amino-4H-pyrans: a retro-Diels-Alder reaction pattern. Rapid Communications in Mass Spectrometry 14(19): 1783-1786

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.


PMID: 11006585

DOI: 10.1002/1097-0231(20001015)14:19<1783::AID-RCM92>3.0.CO;2-1

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