4- Methoxy-5-nitropyrimidine amination

The delicate balance between adduct formation at position 2 or at position 4 is shown in the amino-dehydrogenation of 4-methoxy-5-nitropyrimidine. The course of the amination is found to temperature dependent. Treatment with liquid ammonia/permanganate at —60° to —70 °C gave 2-amino-4-methoxy-5-nitropyrimidine, while at +20 °C 6-amino-4-methoxy-5-nitropyrimidine is obtained (Scheme 18) (83JOC1354). This result indicates that at low temperature the C-2 adduct is the kinetically favored one and at room temperature the C-4 adduct is thermodynamically favored. 

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