Simple, clean and
fast photoconversion of aniline-derived squaramides
was achieved by flashlight illumination. UV irradiation enabled the
photochemical squaramide ring-opening to generate 1,2-bisketenes,
which DMSO trapped as the nucleophilic oxidant. The only photoproducts
isolated were 3,4-arylamino maleic anhydrides, which present conformational
preferences very different from those of their parent squaramides.
Similar photoconversion was achieved in MeOH. The UV-mediated time-dependent
anion transport inhibition was demonstrated, establishing a new approach
for modulating the transport abilities of AD-squaramides.