A facile and practical synthesis of triazolo(4,3-a)pyrimidines using Fe2O3 based nanocatalyst

Aminoazoles have been recognized as excellent building blocks for MCRs due to the presence of several nucleophilic centers with different reactivity [1]. Particularly, 3-aminotriazoles and 5-aminotetrazoles have been extensively explored as substrates for various MCRs. On the other hand, triazole derivatives have been the object of intense investigations in medicinal chemistry and belong to a major class of natural heterocyclic compounds, because of their remarkable activity. For example, 1,2,3-triazoles have found widespread use in pharmaceuticals and agrochemicals [2]. In addition, based on the extensive researches, it has also been observed that triazole derivatives include significant biological activities such as aticancer [3], antitubercular [4], antifungal, antibacterial, anti-HIV [5], anti-inflammatory, antimalarial and antioxidant activity [6]. Owing to the important applications of triazole derivatives in synthetic and medicinal chemistry, and our continued interests for the synthesis of biologically important products [7-9], herein, we report a new and practical method for the synthesis of triazolo(4,3-a)pyrimidine derivatives by the reaction of 3-amino-1,2,4-triazole, ethyl acetoacetate and aryl aldehydes in the presence of Fe2O3@CuFAp nanocatalyst (Scheme 1). This new method furnished the desired triazolopyrimidines in excellent yields and short reaction times. All products were characterized by IR, 1H NMR and 13C NMR analyses.