Silica Sulfuric Acid / Ethylene Glycol: An Efficient Eco-Friendly Catalyst For One-Pot Synthesis Of Tricyclic And Tetarcyclic Dihydropyrimidine Derivatives

A SIMPLE and efficient eco-friendly chemical method was developed for the synthesis of series of tricyclic and tetarcyclic dihydropyrimidine derivatives in excellent yields using a one-pot, multi-component reaction in the presence of catalyst silica sulfuric acid / ethylene glycol. Tricyclic dihydropyrimidine derivatives (benzo[4,5]imidazo[1,2-a]pyrimidines derivatives) were synthesized in high yield and high purity in short reaction times by the reaction of 2-aminobenzimidazole, aldehydes and ethyl acetoacetate in the presence of silica sulfuric acid / ethylene glycol. Tetracyclic dihydropyrimidine derivatives (benzo[4,5]imidazo[1,2-a]pyrimido[4,5-d]pyrimidin-4(1H)-ones) were synthesized by the reaction of 2-aminobenzimidazole, aldehydes and cyanoacetamide in the presence of Silica sulfuric acid / ethylene glycol. This present new protocol offers shorter reaction time, high yields and low cost. This method provides much improved protocol over the already existing methods.