Nitropyridylnaphthalene is the central intermediate for the synthesis of naphthonaphthyridine
and benzo-δ-carboline. Whereas the Cadogan reaction gives the carboline, transformation
of the nitro group to iodo followed by oxidation and cyclization results in an iodonium
salt. A twofold Pd-catalyzed amination leads to the naphthyridine.
Key words
amination - fused-ring systems - heterocycles - iodine - palladium - catalysis