ONE-POT GREEN SYNTHESIS OF 3′-(2-AMINOBENZIMIDAZOLYL)-2-PHENYL SPIRO[4H-BENZOPYRAN-4,2′-THIAZOLIDIN]-4-ONES AND ACYLATION USING TRIFLUOROACETIC ANHYDRIDE

An expeditious one-pot synthesis of a novel heterocyclic system, 3'-(2-aminobenzimidazolyl)-2-phenyl spiro[4H-benzopyran-4,2'-thiazolidin]-4-ones, has been accomplished by condensing substituted hydrazinobenzimidazole, flavanone, and mercaptoacetic acid by conventional heating in ethanol or toluene, and in an ionic liquid, viz., 1-butyl-3-methyl-imidazolium hexafluorophosphate. Excellent yields (85%-90%) and higher purity are obtained in the ionic-liquid-mediated synthesis as compared with the conventional procedure (55%-60%). Further, these compounds were acylated with trifluoroacetic anhydride. The structures of the compounds were confirmed by IR, H-1 NMR, C-13 NMR, mass spectral data, and elemental analysis. The compounds, upon evaluation for their antibacterial, antifungal, and insecticidal activities, exhibited excellent results.