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(l) / -33 °C 2: 86 percent / Na2S2O4 / H2O / 24 h / Heating 3: 84 percent / acetic anhydride / 2 h / Heating 4: 86 percent / xanthine oxidase (AXO) / 120 h / 4N NaOH, potassium phosphate buffer, pH 8.0 View Scheme

With  ammonia T=-33°C;   

Multi-step reaction with 2 steps 1: 96 percent / NH3(l) / -33 °C2: 86 percent / Na2S2O4 / H2O / 24 h / Heating  

Multi-step reaction with 3 steps 1: 96 percent / NH3(l) / -33 °C2: 86 percent / Na2S2O4 / H2O / 24 h / Heating3: 67 percent / dimethylformamide / 12 h / 160 °C  

Multi-step reaction with 2 steps 1: 96 percent / NH3(l) / -33 °C2: 74 percent / dimethylformamide / 16 h / 160 °C