Synthesis and Antifungal Activity of Some Novel (E)-2, 3-Dihydro-3- [(phenylamino) methylene]-4H-1-benzothiopyran-4-ones

A series of novel (E)-2,3-dihydro-3-[(phenylamino)methylene]-4H-1-benzothiopyran-4-ones has been synthesized by using 2,3-dihydro-4H-1-benzothiopyran-4-ones as the starting material. The structures of the new compounds are characterized by UV-vis, IR, HRMS, 1H NMR, and 13C NMR. 2D NMR spectroscopic studies revealed that at room temperature, these compounds rather exist in the keto-enamine than in the Schiff base form. The synthesized compounds were evaluated against two species of fungi in vitro by agar double dilution method. The results of antifungal screening revealed that the MIC value of (E)-8-chloro-2,3-dihydro-3-[(4-nitrophenylamino)methylene]-4H-1-benzothiopyran-4-one (4j) against Candida albicans is 32μg· ml-1 while the control Fluconazole is 64 μg· ml-1.