Synthesis of some novel pyrazoline‐thiazole hybrids and their antimicrobial activities

A series of novel thiazolyl pyrazolines 7a‐h, 9a‐f, and 11a‐f have been synthesized by the reaction of thioamide derivatives 5a,b with 1‐aryl‐2‐bromoethanones 6a‐d, chloroacetones 8a‐c, and hydrazonoyl chlorides 10a‐c. Additionally, pyrazoles 15a‐c and 20 were prepared starting from enaminone 13. These newly synthesized compounds were screened for their in vitro antibacterial activity against four bacterial species. Compound 11b showed a moderate activity against Klebsiella pneumoniae. Compounds 7c and 11c revealed a moderate activity against Pseudomonas aeruginosa. In addition, the antifungal activity of the newly synthesized compounds was determined against five fungal strains. Compounds 7e, 7g, and 11e showed a good activity against Aspergillus flavus and Penicillium expansum.