Retro Diels-Alder Fragmentation Research Articles

Application de la Spectrométrie de Masse en Serie Hétérocyclique. Système N‐Phenyl‐3,6‐Dihydro‐2H‐1,2‐Oxazine

AbstractThe behaviour of some N‐pheny 1‐3, 6‐dihydro‐2H‐ 1, 2‐oxazines is examined under electron impact. These compounds undergo essentially two competitive reactions : 1) a thermal elimination of water which leads to the corresponding N‐phenylpyrrole, as it is proved by the comparison of the metastable ratios evaluated on the oxazine‐H2O⌉·+fragment ions and on the N‐phenylpyrrole itself; 2) a retro Diels Alder fragmentation giving the nitrosobenzene and the butadienyl system.

Spectroscopie de masse des gem-diesters épimères

The analysis of mass spectra of three 2-substituted dihydropyran gem-diesters is presented. The retro-Diels–Alder fragmentation, absent in the other members of the group, was identified. The major fragmentation was the aromatization of the dihydropyran ring.