Abd El-Haleem M. Hussein, Abu-Bakr A. El-Adasy, Ibrahim S. A. Hafi , Esam A. Ishak, Emad H. Gawish1, Mohamed S. A. El-Gaby
Purpose: The main objective of the present research study is to synthesize some novel thiazole , thiazolo [3,2-a] pyridine and thiazolo-[3',2':1,6]pyrido[2,3-d]pyrimidine derivatives and evaluate them for their Antimicrobial effect. Methods: Condensation of 4-phenylmercaptobenzaldehyde 2 with thiosemicarbazide afforded the new thiosemicarbazone derivative 3. Heterocyclization of thiosemicarbazone 3 with various α-halocarbonyl compounds furnished the novel thiazole derivatives 5, 6 and 7. Compound 2 was condensed with 2- cyanomethylene-4-thiazolidinone 8 to yield the 4-thiazolidinone derivative 9. Cyclocondensation of compound 9 with arylidenemalononitrile (1:1 molar ratio) afforded the novel thiazolo [3,2-a] pyridine derivatives 10a-c. Ternary condensation of compound 2, malononitrile and thioglycolic acid (2:2:1 molar ratio) yielded the thiazolo[3,2-a]pyridine derivative 12. Compound 12 was cyclized with formic acid and formamide to yield the thiazolo-[3',2':1,6]pyrido[2,3-d]pyrimidine derivatives 13 and 14, respectively. The structures of the newly synthesized compounds were confirmed on the basis of analytical and spectral data. Some of the prepared compounds 3, 5, 7, 9, 10a,b and 12 were tested in vitro against bacterial and fungal strains. Results: The results of antimicrobial screening data revealed that most of the synthesized compounds showed varying degrees of inhibition against both bacteria and fungi. Conclusion: New thiazole and thiazolo[3,2-a]pyridine derivatives were prepared from easily accessible starting materials. Some newly synthesized compounds were evaluated for their antibacterial and antifungal activities in vitro against four bacteria and two fungi.