Nitro-1,5-Naphthyridines

The main use of nitro-1,5-naphthyridines has been as precursors for 1,5-naphthyridinamines. However, the presence of a powerfully electron-withdrawing nitro group is often of use to activate adjacent leaving groups such as halogeno toward nucleophilic replacement reactions. 

The mass spectral fragmentation patterns of a variety of nitro-1,5-naphthyridine derivatives have been reported.434,492 

Some such nitro derivatives have been prepared by primary synthesis (see Chapter 1). Other preparative routes are illustrated in the following examples. 

The Naphthyridines The Chemistry of Heterocyclic Compounds, Volume 63, by D.J. Brown Copyright 2008 John Wiley Sons, Inc. 

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The added electron deficiency at positions 2 and 5 in the nitro-1,6-naphthyridines together with the resonance stabilization of the hydrated cations (150<—>151 152<—>153) is thus required for covalent hydration. The 3-nitro-1,5-naphthyridine satisfies the first require-... 

Other work has been carried out concerning the amination of 3-nitro-1,5-naphthyridine (46a) with liquid ammonia containing potassium permanganate.27 The 4-amino-3-nitro- 1,5-naphthyridine (50) is obtained in 50% yield. Its precursor, the covalent rr-adduct (47a), has been detected by NMR spectroscopy (see Section II,B,3). 

Nitro-1,5-naphthyridin-4( 1H)- one gave 4-chloro-8-nitro-1,5-naphthyridine (20) (PC15, POCI3, reflux, 75 min 68%).48... 

The silver salt (17) of 3-nitro-1,5-naphthyridin-2(l//)-one gave 2-ethoxy-3-nitro-l,5-naphthyridine (18) (neat EtI, reflux, 2 h 20%).837... 

Note This procedure offers an indirect route from 1,5-naphthyridinamines to nitro-1,5-naphthyridines. 

The halogenolysis of a nitro-1,5-naphthyridine (using phosphorus pentachloride) has been recorded in Section 3.1.2. The reduction of nitro-1,5-naphthyridines to... 

Chloro-l, 5-naphthyridin-4( l//)-one 2-Chloro-3-nitro-1,5-naphthyridin-4-amine... 

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