6-AMINOTHIOURACIL (1) reacts in boiling dimethylformamide with cyclic α,β-unsaturated ketons (2) yielding the 7-aryl-10-thioxo-5,6,7,10,11, 12-hexahydro,7-aryl-10-thioxo-5,6,10,11-tetrahydro -9H-benzo [h] pyrimido [4,5-b]quinolin-S-one systems (4,5) and 5-aryl-2-thioxo-1,2,3, 5,6,7,8,9,10,11-decahydro-, 5-aryl-2-thioxo-1,2,3,6,7-,8,9,10-octahydro -cyclohepta [5,6] pyrido[2,3-d]pyrimidin-4-one(8,9), respectively. The latter pyridopyrimidines reacted with chloroacetic acid in presence of an aldehyde to furnish a 10- arylidene -7- aryl- 5,6- dihydro-11- thia-8a,12,13- triazabenzo- [a] cyclopcnia [i] anthracene- 8,9- dione or 2-arylidene -5- aryl- 7,8, 9,10- tetrahydro -6H-1-thia-3a, 11,12-triaza-cyclohepta [b] cyclopenta [g] naphthalene -3,4-dione (10,11). The reaction with halo-derivatives such as methyliodide,3-chloro-2,4-pentanedione furnished the alkylaled pyrimidines 12,14, 16,17, 19,20. The latter products reacted with hydrazine hydrate to give the hydrazine derivatives 21. The cyclization of 12, 14 to 13, 15 using acetic anhydride/pyridine have been reported.