2- Ethoxy-3-nitro-1,5-naphthyridine, catalytic

Catalytic hydrogenation (Pd/C) of 2-chloro-3-nitro-l,5-naphthyridine (125, R = Cl) in methanolic solution afforded 3-amino-l,5-naphthyridine (126, R = H, 74%) isolated in the form of its trihydrochloride (40MI1). Similar Pd/C hydrogenation of 2-ethoxy-3-nitro-l,5-naphthyridine (125, R = OEt) gave 3-amino-2-ethoxy-l,5-naphthyridine (126, R = OEt, 47%) (80RTC83). Reduction with tin(II) chloride in hydrochloric acid also leads to 126, (R = OEt, 73%) (63RTC997). 

Catalytic reduction of 3-nitro-7-phenyl-l,8-naphthyridin-2(lH)-one (136) with palladium on carbon in 2-ethoxy ethanol gave the l,2-di(l,8-... 

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