Dipyreno- and diperyleno-anthracenes from glyoxylic Perkin reactions.

Twofold Perkin condensation of 2,5-dibromophenylene-1,4-diacetic acid with arylglyoxylic acids followed by cyclo-dehydrobromination leads to dipyreno- and diperyleno-anthracene tetraesters and diimides. The imides show surprisingly large absorption shifts versus the esters, illustrating that electron-withdrawing substituents at the anthracene unit efficiently impart long wavelength absorption in such electron-deficient graphene nanoribbon fragments.