Synthetic approaches
have been established to navigate the inherent synthetic
challenges associated with using “sticky” and aggregating
purines and pyrimidines as π-building blocks in Pd-catalyzed
cross-coupling reactions. Protocols have specifically allowed
addition of three (A, G, U) of the nucleobase heterocycles to
the terminal positions of standard thiophene-containing π-
conjugated sequences; attempts to prepare cytosine (C)
derivatives remain in progress.