Synthesis of 2-thiooxopyrimido-[4,3-d]-quinoline-4-one derivatives

Abstract

To study the synthesis route of2-Thiooxopyrimido-[4,3-d3-quinoline-4-one and its derivativeswhich was expected to be the ligands of benzodiazepine receptor. The formation of 2-Thiooxopyrimido-[4,3-d]-quinoline-4-oneand its derivatives proceeded through 4 steps. Firstly, thederivatives of quinoline were produced from the reaction ofDiethyl ethoxymethylenemalonate and Aniline or Anilinederivatives and the product was achieved by thermal cyclization.Secondly, 4-Hydroxyquinoline derivatives were chlorinated withthionyl chloride or phosphorous oxychloride to afford4-Chloroquinoline intermediates. Thirdly, the nucleophilicsubstitution reaction of potassium thiocyanate with4-Chloroquinoline gave 4-Isothiocyanatoquinoline. Finally, thedesire products were succeeded by cyclization reaction ofisothiocyanate group and ester group with ammonia or aminederivatives. And another method for synthesized the derivativesat position 3 was by alkylation of 2-Thiooxopyrimido-[4,3-d]-quinoline-4-one in base. The oxidation reaction could changethiooxopyrimidine ring to pyrimidine ring. The structure of the synthesized compounds were confirmedby IR, HNMR and MS techniques.