Design and Synthesis of (E)-4-(2-Phenyl-2H-chromen-3-yl)but-3-en-2-ones and Evaluation of their In Vitro Antimicrobial Activity

2H-Chromene and its derivatives are an important class of organic compounds due to their wide range of biological activities such as antimicrobial, antiviral, antiimflamatory and antitubercular agents. In the present work we have synthesized ten new 2H-chromene derivatives [(E)-4-(2-phenyl- 2H-chromen-3-yl)but-3-en-2-one and its substituted analogues] following aldol condensation of 2Hchromene- 3-carbaldehydes with acetone. These products have been characterized by means of spectral data (1H, 13C, IR, Mass). The structure of one new compound (E)-4-(6,8-dichloro-2-phenyl-2H-chromen-3-yl)but-3-en-2- one was confirmed by X-ray analysis and the product was subsequently subjected to the in vitro evaluation of antimicrobial activity against two Gram positive bacteria Streptococcus mutans (MTCC 497) and Streptococcus pyogenes (MTCC 1926) and three Gram negative bacteria Vibrio cholera (MTCC 3909), Shigella flexneri (MTCC 1457) and Salmonella enteric typhi (MTCC 1252). The obtained results from in vitro antimicrobial assays by broth dilution method indicated that many compounds under study exhibited excellent activity against all the microorganisms in comparison to standard kanamycin.