SYNTHESIS OF SOME PYRIDINE an‎d PYRIMIDINE DERIVATIVES VIA MICHAEL-ADDITION

Synthesis of pyridine and pyrimidine analogues 4 6-9 were achieved by Michael-addition ofcompounds containing either active methylene groups like, malononitrile, ethyl cyanoacetate and 1-tetraloneor compounds containing active hydrogen atoms like, guanidine in the presence of an oxidizing agent and thiourea to 2-arylmethylidine-1-tetralone and 2-arylmethylidine-6-methoxy-1-tetralone (2) (enones).Addition of malononitrile in piperidine at room temperature to 2 gave 2-amino-3-cyano-naphtho[1,2-b]pyran derivatives 3 which were converted to 4 upon treatment with sodium methoxide. Addition of malononitrile in sodium alkoxide or sodium hydroxide to 2 gave 4. Cyclization of 3 a with aceticanhydride in the presence of conc. H2SO4 gave the naphtho-pyrano[2,3-d]pyrimidin-8-one (5).Condensation of the pyrimidine thione derivatives 9 with chloroacetic acid gave the 3-oxobenzo[h]thiazolidino[2,3-b]quinazoline derivatives (10), which were reacted through their active methylene groups with aromatic aldehydes to give the arylidine derivatives 11. These compoundes were also prepared in one step by reacting 9 with chloroacetic acid and aromatic aldehydes. Condensation of 9 with 3-bromopropanoic acid gave 4-oxo-benzo[h]1,3-thiazino[2,3-b]quinazoline derivatives (12). The structures of the prepared compounds were mainly confirmed on the basis of spectroscopic methods.