Synthesis of benzimidazoles bearing oxadiazole nucleus as anticancer agents.

Starting from 4-(1H-benzo[d]imidazol-2-yl)-4-oxobutanehydrazide (1), twenty new 1-(1H-benzo[d]imidazol-2-yl)-3-(1,3,4-oxadiazol-5-substituted derivatives-2-yl)propan-1-ones (1b-A(7)(-)(26)) were synthesized under microwave irradiation in good yields. Further, compound 1b-A(7) was reacted with different secondary amines under microwave irradiation to produce five novel 1-(1H-benzo[d]imidazol-2-yl)-3-(5-(methyl substituted)-1,3,4-oxadiazol-2-yl)propan-1-ones (1b-A(7a)(-)(e)). The title compounds were screened for their in vitro anticancer activity at National Cancer Institute (NCI), USA; at a single dose (10 μM) in NCI 60 cell line panel and results showed significant to good anticancer activity. One compound, 1b-A(18) (NSC: 759205), 1-(1H-benzo[d]imidazol-2-yl)-3-(5-(2,4-dichlorophenyl)-1,3,4-oxadiazol-2-yl)propan-1-one, emerged as lead compound; it was selected for five-dose level screening and found to have significant growth inhibition activity.