Fragmentation de Benzodioxannes-1,3 Diversement Substitues en 2,4

Les benzodioxannes-1, 3 diversement substitues en 2,4 subissent deux coupures de ‘retro’ Diels-Alder: l'une classique, l'autre avec migration d'hydrogene. Under electron-impact, two ‘retro’ Diels-Alder fragmentation paths are observed in the spectra of 2,4- substituted 1,3-benzodioxan; one with normal ‘retro’ Diels-Alder reaction and the other with hydrogen transfer.