1: With sodium methylate in toluene T=40 - 50°C; 6 h; 2: With potassium hydroxide in methanol; water 6 h; Heating / reflux; 3: With hydrogenchloride T=25°C; pH=1;

thionyl chloride; N,N-dimethyl-formamide T=50 - 85°C; 3.75 h;