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Abstract 1H-Benzo[d]imidazole (2) was prepared by treatment of ophenylenediamine (1) in 98% formic acid either by reflux or by microwave irradiation followed by basification by sodium carbonate to give white prisms 2 in 88-98% yield (Scheme 1). Ethyl 2-(1H-benzo[d]imidazol-1-yl)acetate (3) was synthesized by treating of 2 with ethyl choloroacetate in dry acetone and anhydrous K2CO3 either by reflux or by microwave irradiation to afford white powder 3 in 71-98% yield (Scheme 1). The respective ester 3 in absolute ethanol and hydrazine hydrate was refluxed or microwave irradiated to afford 2-(1H-benzo[d]imidazol- 1-yl)acetohydrazide (4) 89-98% yield (Scheme 1). A solution of the respective hydrazide 4 in CS2 and aqueous solution KOH and ethanol was refluxed for 4h and the solvents were evaporated to dryness under reduced pressure. The obtained solid was dissolved in water and acidified with conc. HCl. The precipitate was filtered off. Washed with water, and recrystallized from ethanol to afford 5-[(1H-benzo[d]imidazol-1-yl)methyl]-1,3,4-oxadiazole-2-thiol (5) as yellow powder in 83% yield (Scheme 1). |