Fused pyridine derivatives R 0450 Efficient Synthesis of 1,2,4-Triazolo[4,3-a][1,8]naphthyridines under MicrowaveIrradiation. -The oxidative cyclization of hydrazones (III) with chloramine-T under microwave irradiation proceeds clean without formation of any by-products. Using this procedure, the triazolonaphthyridines (IV) are obtained with a higher degree of purity, and in most cases no further purification is needed. Further features of this procedure are the operational simplicity, short reaction time, high yields as well as the inexpensive and nontoxic reagents. -(MOGILAIAH*, K.; SWAMY, T. K.; KUMAR, K. S.; J.