Synthesis and reaction of pyrido[2,3-d] pyrimidine with related thiazolo and enaminonitrile derivatives

ABSTRACT

In a one-pot synthesis pyrido[2,3-d] pyrimidine-2-thione derivatives [3a-c] were prepared via the reaction of a mixture of 6-aminothiouracil [1], cyclooctanone and a proper aldehyde in dimethylformamide. Compound 3 reacted with a mixture of chloroacetic acid and aromatic aldehyde in acetic acid and acetic anhydride to give 6-aryl-thiazolo [4,5-a] cyclooctenopyrido [2,3-d] pyrimidine -3,5-diones [4a-c]. Compound 3b underwent cyclization on boiling with 3-chloro-2,4-pentandione in acetic anhydride/pyridine solution to give 5. On the other hand, compound 3b reacted with bromo-malononitrile to give enaminonitrile [6] Compound 6 reacted also with aliphatic acids to give 14-[chlorophenyl]-2-[unsub./methyl] pyrimido[4',5'4,5] thia-zolo[3,2-a] cyclooctenopyrido [23-d] pyrimidine- 4,15- dione [8a,b]