Abstract:

A series of Pyrimido[1,2-a]benzimidazoles derivatives were synthesized by the reaction of 2-aminobenzimidazole with an aldehyde in the presence of malononitrile via Microwave Irradiation or classical heating conditions in water without using any catalyst. The results showed the optimal conditions of the reaction: the mole ratio of three component (malononitrile/aldehyde/2-aminobenzimidazole) is 1.1 and the microwave irradia- tiontime was 6 min with the power of 400 W, The total yield of 1,4-dihydro -pyrimido-[1,2-a]benzimidazole was above 85%. The reaction rate was increased by 70 times against ordinary heating. Their optical characteristics are tested by the fluorescence spectrum. The peaks at the range from 480nm to 550nm are observed in their fluorescence emission spectrum.

Key words: Microwave Irradiation, dihydropyrimido[1,2-a]benzimidazole, water, fluorescence