Iptycene-Derived Pyridazines and Phthalazines

The synthesis of new heterocyclic oligo(phenylene) analogues based on soluble, nonaggregating 1,2-diazines is reported. Improved palladium-catalyzed reductive coupling methods were developed to allow
for the preparation of large quantities of iptycene-derived bipyridazines and biphthalazines, and the
controlled synthesis of well-defined oligomers up to sexipyridazine. Crystallographic, spectroscopic, and
computational evidence indicate that in these analogues, hindrance at the ortho position is relaxed relative
to poly(phenylenes). The resulting building blocks are promising for incorporation in conjugated electronics
materials, and as new iptycene-derived ligands for transition metals.