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Benzopyrones—V Mass spectra of some ethyl 4‐oxochromen‐2‐carboxylates and related compounds
Author(s) -
Barker G.,
Ellis G. P.
Publication year - 1971
Publication title -
organic mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 0030-493X
DOI - 10.1002/oms.1210050712
Subject(s) - carboxylate , mass spectrum , chemistry , chromone , medicinal chemistry , base (topology) , ion , carboxylic acid , infrared spectroscopy , stereochemistry , polymer chemistry , organic chemistry , mathematical analysis , mathematics
The mass spectra of 23 chromone derivatives are recorded and interpreted. Most of these are ethyl 4‐oxochromen‐2‐carboxylate derivatives, which with two exceptions, show the molecular ion as the base peak. In the spectrum of the unsubstituted ester (XVIII), the other most important fragments are [M—C2H4], [M—OEt], [M—C2H4—CO], [M—CO2Et + 1] and the benzocyclopropenyl ion. 6‐Hydroxy‐2‐methylchromone and several of its derivatives undergo a retro‐Diels‐Alder reaction (R.D.A.) and also lose the carbonyl group. Ethyl 6‐amino‐4‐oxochroman‐2‐carboxylate (XXIII) shows an R.D.A. reaction as well as losing the CO2Et group. The mass spectrum of 4‐oxochromen‐2‐carboxylic acid has been studied.