1: 67 percent / dimethylformamide / 12 h / 160 °C 2: 45 percent / 1) 90percent aq. Na2S2O4, 0.5M NaOH, 15 min, reflux; 2) O.1M NaOH, O.1M KMnO4, r.t., 10 min 3: 87 percent / xanthine oxidase (AXO) / 120 h / 4N NaOH, potassium phosphate buffer, pH 8.0 View Scheme

1: 89 percent / Na2S2O4 / H2O / 24 h / Heating 2: 32 percent / acetic anhydride / 2 h / Heating 3: 87 percent / xanthine oxidase (AXO) / 120 h / 4N NaOH, potassium phosphate buffer, pH 8.0 View Scheme

1: 86 percent / Na2S2O4 / H2O / 24 h / Heating 2: 67 percent / dimethylformamide / 12 h / 160 °C 3: 45 percent / 1) 90percent aq. Na2S2O4, 0.5M NaOH, 15 min, reflux; 2) O.1M NaOH, O.1M KMnO4, r.t., 10 min 4: 87 percent / xanthine oxidase (AXO) / 120 h / 4N NaOH, potassium phosphate buffer, pH 8.0 View Scheme

1: 89 percent / NH3(l) / 3 h / -33 °C 2: 89 percent / Na2S2O4 / H2O / 24 h / Heating 3: 32 percent / acetic anhydride / 2 h / Heating 4: 87 percent / xanthine oxidase (AXO) / 120 h / 4N NaOH, potassium phosphate buffer, pH 8.0 View Scheme

1: 96 percent / NH3(l) / -33 °C 2: 86 percent / Na2S2O4 / H2O / 24 h / Heating 3: 67 percent / dimethylformamide / 12 h / 160 °C 4: 45 percent / 1) 90percent aq. Na2S2O4, 0.5M NaOH, 15 min, reflux; 2) O.1M NaOH, O.1M KMnO4, r.t., 10 min 5: 87 percent / xanthine oxidase (AXO) / 120 h / 4N NaOH, potassium phosphate buffer, pH 8.0 View Scheme

1: 96 percent / NH3(g) / propan-1-ol / 36 h / Ambient temperature 2: 89 percent / Na2S2O4 / H2O / 24 h / Heating 3: 32 percent / acetic anhydride / 2 h / Heating 4: 87 percent / xanthine oxidase (AXO) / 120 h / 4N NaOH, potassium phosphate buffer, pH 8.0 View Scheme

1: 96 percent / NH3(g) / propan-1-ol / 36 h / Ambient temperature 2: 86 percent / Na2S2O4 / H2O / 24 h / Heating 3: 67 percent / dimethylformamide / 12 h / 160 °C 4: 45 percent / 1) 90percent aq. Na2S2O4, 0.5M NaOH, 15 min, reflux; 2) O.1M NaOH, O.1M KMnO4, r.t., 10 min 5: 87 percent / xanthine oxidase (AXO) / 120 h / 4N NaOH, potassium phosphate buffer, pH 8.0 View Scheme

1: 45 percent / 1) 90percent aq. Na2S2O4, 0.5M NaOH, 15 min, reflux; 2) O.1M NaOH, O.1M KMnO4, r.t., 10 min 2: 87 percent / xanthine oxidase (AXO) / 120 h / 4N NaOH, potassium phosphate buffer, pH 8.0 View Scheme