3- Nitro-l,6-naphthyridine

Proton magnetic resonance spectra (in CDCI3) of 3-nitro-l,5-naphthyri-dine (84a), 3-nitro-l,6-naphthyridine (84f), and 8-nitro-l,6-naphthyridine (81) have been measured and analyzed [66JCS(B)750]. 

Tlie effect of substituents on chemical shifts in H NMR spectrum of 4-chloro-3-nitro-l,6-naphthyridine (78b), when compared with those of the parent 1,6-naphthyridine, show that all corresponding proton signals in 78b are shifted downfield in the range of 0.09 to 0.72 ppm. Tlie downfield of H-2 is particularly large 0.72 ppm (75MI1). 

Nitropyrimidine (147) underwent a Diels-Alder-type addition by the enam-ine, l-acetyl-4-(pyrrolidin-l-yl)-l,2,3,6-tetrahydropyridine (146), and subsequent reactions to afford 6-methyl-3-nitro-5,6,7,8-tetrahydro-l,6-naphthyridine (148, R = Ac) (reactants, EtOH, reflux, 3 h 48%) and thence deacetylation to 3-nitro-5,6,7,8-tetrahydro-l,6-naphthyridine (148, R = H) (6M HC1, reflux, 90 min 89%) and oxidation to 3-nitro-l,6-naphthyridine (substrate, AcOH, EtOH, reflux, I2/EtOH I2EtOHJ, dropwise, reflux. 2 h 64%)656... 

Chloro- (27, R = C1) gave 2-ethoxy-3-nitro-l,6-naphthyridine (27, R = OEt) (EtONa, EtOH, 20°C, 3 h 60%) 819 2-chloro- (28, R = Cl) gave 2-methoxy-l,6-naphthyridine-3-carbonitrile (28, R = OMe) (MeONa MeOH, reflux, 1 h 87%).247 Note the activation by an electron-withdrawing group in these examples. 

Bromo- (35, R = Br) with dimethylamine gave 4-dimethylamino-l,6-naphthyr-idine (35, R = NMe2) (neat reactants, 135°C, sealed, 16 h %)1057 but 4-chloro- (35, R = C1) gave 4-piperidino-l,6-naphthyridine [35, R = N(CH2)5] apparently under milder conditions (neat reactants, 95°C, 5 min %)1067 4-chloro-3-nitro-l,6-naphthyridine (36, R = C1) gave 3-nitro-l,6-naphthyridina-mine (36, R = NH2) (NH3/MeOH, 110°C, sealed, 4h 75%).819... 

Nitro-1,6-naphthyridine (11, R = H) gave 3-nitro-l,6-naphthyridin-4-amine (11, R = NH2) (KMn04, liq NH3, 55% no other details).514... 

Ethoxy-1,6-naphthyridine 2-Ethoxy-3-nitro-l,6-naphthyridin-4-amine 2- Ethoxy-3-nitro- 1,6-naphthyridine Ethyl 5-amino-7-benzylseleno-8-cyano-2-methyl-1,6-naphthyridine-3-carboxylate Ethyl 6-amino-2-methyl-5-oxo-5,... 

Naphthyridin-2(177)-one 6-oxide 3-Nitro-l,6-naphthyridin-2-amine 3-Nitro-l,6-naphthyridin-4-amine... 

Nitro-l,6-naphthyridine A-d-3 -N itro-1,6-naphthyridine 8-Nitro-1,6-naphthyridine... 

Aromatization of the nitro compound (102) giving 3-nitro-l,6-naphthyridine (103) (24% yield) has been achieved by treatment with iodine <89T2693>. 

Deuterio-3-nitro-l,6-naphthyridine (168) was prepared from 4-chloro-3-nitro-l,6-naphthyridine (166) by a reaction with tosyl hydrazide and subsequent hydrolysis of the 4-tosylhydrazino derivative (167) with Na2C03/ D20 solution (83RTC359). 7-Deuterio-l,8-naphthyridin-2(lH)-one was prepared by heating l,8-naphthyridin-2(lH)-one with deuterium oxide at 230°C for 35 h (85JHC761). This deuterio compound could be converted into 2-chloro-(or 2-ethoxy-) 7-deuterio-3,6-dinitro-l,8-naphthyridine. 

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