Mannich reaction in the synthesis of N,S-containing heterocycles. 16.*Synthesis of derivatives of tetra-hydropyrido[1,2-a][1,3,5]triazine and 5,6,12,13-tetra-hydro-1H,8H-dipyrido[1,2-a:1',2'-e][1,3,5,7]tetrazocine

The aminomethylation of 6-amino-4-aryl-2-thioxo-1,2-dihydropyridine-3,5-dicarbonitriles by the action of primary amines and an excess of formaldehyde under conditions of base catalysis was studied. It was found that the structure and yields of the products depend largely on the structure of the initial amine and also on the ratio of the reagents and reaction conditions. In the case of alkyl- or arylalkylamines, 8-aryl-3-alkyl(arylalkyl)-6-thioxo-1,3,4,6-tetrahydro-2H-pyrido[1,2-a][1,3,5]triazine-7,9-dicarbonitriles were obtained, whereas when aromatic amines were used 3,10-diaryl-1,8-dithioxo-5,6,12,13-tetrahydro-1H,8H-dipyrido[1,2-a:1′,2′-e][1,3,5,7]tetrazocine-2,4,9,11-tetracarbonitriles or their mixtures with the above-mentioned pyrido[1,2-a][1,3,5]triazines were obtained. Dipyrido[1,2-a:1′2′-e]-[1,3,5,7]tetrazocine derivatives were also synthesized by direct condensation of 6-amino-4-aryl-2-thioxo-1,2-dihydro-pyridine-3,5-dicarbonitriles with formaldehyde.