1: triethyl ethane-1,1,2-tricarboxylate With sodium methylate in methanol T=20°C; 3 h; 2: methanimidamide monoacetate in methanol T=20 - 68°C; 3: With hydrogenchloride in methanol T=10 - 15°C; pH=1.5 - 2;

sulfuric acid T=85°C; 24 h;

triethylamine; trichlorophosphate in toluene T=110 - 115°C; 3 h;