in proof alcohol T=20 - 55°C; 94 h;

sodium ethanolate in methanol 6 h; Heating / reflux;

ammonium acetate in N,N-dimethyl-formamide

1: 4-(4-chloro-2-fluorophenoxy)benzamidine With sodium ethanolate in ethanol Heating / reflux; 2: 4-dimethylamino-2-oxo-but-3-enoic acid methyl ester; ethyl 4-(dimethylamino)-2-oxo-3-butenoate in ethanol 21 h; Heating / reflux; 3: With sulfuric acid in ethanol 3 h; Heating / reflux;