Amino-2,6-naphthyridines acylation

Azolo[l,8]naphthyridines. The reactions of the chloronaphthyridine 229 with o-phenylenediamine at 200 °C and with sodium azide in acetic acid give the fused-ring products 230 and 231, respectively (Scheme 54) <2003IJB192>. Amino acid-substituted naphthyridines can be cyclized to the fused imidazolones 232 upon treatment with phosphorus oxychloride and under microwave irradiation (Equation 62) <2002SC857>. Acylation of 2-hydrazino-naphthyridines followed by heating gives W-acyl compounds which are cyclized intramolecularly to the [l,2,4]tri-azolo[4,3- ][l,8]naphthyridines 233 (Scheme 55) <1996IJB106>. The same compounds may also be obtained from... 

In contrast to the DDA units described above, there are comparatively few dimeric AAD modules. Zimmerman and co-workers have developed a convenient synthesis of 2,6-diaminopyridine-3-carboxaldehyde (DPC), which undergoes a Friedlander reaction with ketones to produce 2-amino-1,8-naphthyridines [37]. For example, the reaction of DPC with tetra-cyclo[6.3.0.0 0 ]undecane-2,7-dione followed by acylation with octanoic anhydride produced 55. A number of diketones reacted similarly with DPC to produce bis-2-amino-l,8-naphthyridines with varying chromophore orientations. 

---