Synthesis and biological evaluation of novel active arylidene derivatives of 5,6-dihydro-4<Emphasis Type="Italic">H</Emphasis>-cyclopenta[<Emphasis Type="Italic">b</Emphasis>]- and 4,5,6,7-tetrahydrobenzo[<Emphasis Type="Italic">b</Emphasis>]-thiophene-2-carboxylic acid

A series of novel arylidene derivatives of 5,6-dihydro-4H-cyclopentab]-thiophene-2-carboxylic acid and 4,5,6,7-tetrahydrobenzob]-thiophene-2-carboxylic acid were synthesized by reacting benzylidene derivatives of chloro aldehyde with 2-mercaptoacetic acid. Benzylidene derivatives of chloro aldehyde were prepared from Vilsmeier reaction of 2-benzylidenecyclopentanone and 2-benzylidenecyclohexanone derivatives, obtained from condensation of various aromatic aldehydes with cyclopentanone and cyclohexanone. All synthesized compounds were characterized by nuclear magnetic resonance (NMR), infrared (IR), and mass spectroscopy and X-ray single-crystal analysis. The synthesized compounds were screened for their in vitro antimicrobial and antifungal activity. Good antimicrobial activity, especially against methicillin-resistant Staphylococcus aureus, was observed for most of the compounds tested. In particular, compound 9f emerged as an effective antibacterial agent and may be a potential candidate for future drug discovery and development.