Dv. Ramana et E. Kantharaj, CYCLOREVERSAL REACTION AND ORTHO INTERACTIONS IN 2-ARYL-4H-3,1-BENZOXAZIN-4-ONES ON ELECTRON-IMPACT, Journal of mass spectrometry., 30(8), 1995, pp. 1195-1200
A cycloreversal reaction, leading to aroyl cations, is the major proce
ss in 2-aryl-4H-3,1-benzoxazia-4-ones under electron impact conditions
. The ortho interaction of the methoxy and the nitro groups in the 2-p
henyl mtaieties in these compounds present the most abundant ions at m
/z 119 and 134, respectively, in their mass spectra as a result of the
transfer of a hydrogen atom from the former and an oxygen atom from t
he latter to the imine nitrogen of the heterocycle. The ion structures
and the mechanisms for the proposed fragmentations are based on high-
resolution data, B/E and B-2/E linked-scan spectra, collision-activate
d decomposition-B/E linked-scan spectra and deuterium labelling.