1: With bromine; triphenylphosphine in isobutyramide T=8°C; 0.75 h; 2: 4-amino-4-deoxy-6-hydroxymethylpteridine in isobutyramide T=20°C; 18 h; 3: 4-amino-benzoic acid With BaO in isobutyramide T=53 - 57°C; 22 - 26 h;