A facile synthesis of some novel thiazoles, arylazothiazoles, and pyrazole linked to thiazolyl coumarin as antibacterial agents

5-bromosalicylaldehyde (1) was reacted with thiosemicarbazide to afford thiosemicarbazone derivative2. The latter underwent cyclocondensation upon reaction with alpha-haloester, alpha-haloketone as well as hydrazonoyl halides affording 1,3-thiazoles and arylazothiazoles3-6, respectively. On the other hand, pyrazolyl thiazolyl coumarin derivatives9a-cand11a-cwas obtained via reaction of hydrazinylthiazole8with acetylacetone, trifloroacetylacetone, ethyl acetoacetate and/or arylazoacetylacetone10a-c, respectively. Furthermore, thiazolotriazine derivative12was accomplished via reaction of8with ethyl 2-(2-phenylhydrazono)-2-chloroacetate. The structures of the newly prepared compounds were elucidated by spectral data. Eleven of the newly synthesized compounds were screened for their antibacterial activity. The results indicated that, compounds5a,5b,9a, 9c, 11band12were strong active toward Gram-positive bacteriaEnterococcus faecalis. Compound5awas strong active toward Gram-positive bacteriaStaphylococcus aureus. Moreover, compounds9b, 11b,and12were strong active toward Gram-negative bacteriaPseudomonas aeruginosa.