A series of new substituted benzo [1, 3] oxazines presenting bulky substituents on the chiral oxazine centre were prepared from isopropyl ketones or substituted cyclohexanones. Laser irradiation of these uncoloured compounds in solution promotes the cleavage of the C–O bond and the opening of the [1, 3] oxazine ring generating a zwitterionic species, incorporating a 3H-indolium cation and a 4-nitrophenolate anion, that absorbs strongly at ...
