Synthesis, characterization and larvicidal activity of novel benzylidene derivatives of fenobam and its thio analogues with crystal insight

Abstract

A series of novel benzylidene derivatives of fenobam (6a-p) and its thio analogues (7a-f) were synthesized and evaluated for their larvicidal activity against the malaria vector Anopheles arabiensis. The newly synthesized compounds were characterized by FT-IR, NMR (1H and 13C), LC-MS, spectral studies, and elemental analysis. Selected compounds from this series were further studied by the single-crystal X-ray method to establish the molecular conformation and investigate the presence of various intra- and intermolecular interactions. The larvicidal activity of these test compounds (6a-p and 7a-f) was analyzed following WHO guidelines. Compounds 1-(4-fluorophenyl)-3-{(2E,5Z)-1-methyl-5-[(5-methylfuran-2-yl)methylidene]-4-oxoimidazolidin-2-ylidene}thiourea (7e), 1-(4-fluorophenyl)-3-[(2E,5Z)-1-methyl-5-{[5-(2-nitrophenyl)furan-2-yl]methylidene}-4-oxoimidazolidin-2-ylidene]thiourea (7f) and 1-(4-fluorophenyl)-3-[(2E,5Z)-1-methyl-5-{[5-(2-nitrophenyl)furan-2-yl]methylidene}-4-oxoimidazolidin-2-ylidene]urea (6l) emerged as promising larvicidal agents exhibiting 85 to 92% larval mortality.