1H-imidazole in N,N-dimethyl-formamide T=80°C; 3 h;

sodium ethanolate; formic acid ethyl ester in ethanol 3 h; Heating;

sodium ethanolate; formic acid ethyl ester in ethanol 3 h; Heating;

1: N-<3-(dimethylamino)propyl>-N'-ethylcarbodiimide hydrochloride / various solvent(s) / 25 °C / half-life value of the ring transformation, other 6-oxo-purines 2: 77 percent / conc. aq. ammonia / 2 h / Ambient temperature View Scheme