ammonium acetate; 1-butylpyridinium tetrafluoroborate T=100 - 110°C; Hantzsch pyridine synthesis; 3 h;

1: acetoacetic acid methyl ester; 2,3-dichlorobenzylaldehyde With piperidine; pyridine-2-carboxylic acid in isopropyl alcohol T=40 - 45°C; 6 h; 2: ethyl aminocrotonate in isopropyl alcohol 4 h; Heating / reflux;