Amino-1,6-naphthyridines spectra

Naphthyridine undergoes NH2" attachment at position 1 at -30°C. The NMR spectrum of the resulting adduct does not change at 20°C. Accordingly, the amination of the same substrate yields 1-amino-2,6-naphthyridine.110 A similar behavior is displayed by 2,7-naphthyridine, attachment of the reagent occurring at position l.110 Also in this case the Chichibabin amination occurs at room temperature at the same position. 

H- and 13C-NMR spectroscopy of a solution of 13 in KNH2/NH3 shows that H-l and C-l have undergone upheld shifts of 4.24 ppm and 83.7 ppm, respectively (Tables II and III).20 This is due to the formation of 1-amino-dihydro-2,6-naphthyridinide (14). Because 2,6-naphthyridine is reported to have the lowest electron density at position 11819 (Table I), the formation of cr-adduct 14 is in good agreement with these calculations. The spectrum of... 

A solution of 2-chloro- and 2-amino-3,5-dinitro-l,8-naphthyridine in liquid ammonia shows the presence of a covalent adduct at C-4, as proved by NMR spectroscopy (83RTC359, 83RTC511, 83JHC9, 85JHC761, 93LAC 471, 00AHC(77)285). The NMR spectrum of a solution of 2-ethoxy-3,5-dinitro-l,8-naphthyridine and 2-chloro-3,5-dinitro-l,8-naphthyridine in liquid ammonia features the presence of two covalent adducts one at C-4 as well as one at C-5. The C-4/C-5 adduct ratio is found to be temperature dependent. For the 2-chloro compound the adduct ratio C-4/C-5 is 60/40 at —45°C, but changes to 40/60 at room temperature. This temperature dependency for the 2-ethoxy compound is more pronounced the C-4/C-5 adduct ratio is 50/50 at —45°C and 85/15 at room temperature. 

The NMR spectrum of 1,7-naphthyridine in liquid ammonia/potassium amide at —40°C showed the presence of the C-2 and the C-8 a-adducts. Increasing the temperature of this mixture from —40°C to +10 °C the mixture irreversibly converts into the C-8 adduct. Addition of potassium permanganate gives 8-amino- 17-naphthyridine. The allylic contribution in the C8-adduct accounts for its higher stability. 

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