Ultrasound-assisted rapid synthesis of 2-aminopyrimidine and barbituric acid derivatives

Novel, inexpensive, and relatively expeditious procedure to achieve the synthesis of different 2-aminopyrimidine and barbituric acid derivatives is presented here, starting from readily available compounds such as guanidine hydrochloride, urea, 1,3-dialkylurea, or thiourea. Under ultrasonic irradiation, base-driven (Na2CO3, NaOH, or NaOC2H5) heterocyclization reactions of the aforementioned substrates with diethyl malonate, diethyl-2-alkyl malonate, pentane-2,4-dione, or ethyl-3-oxobutanoate yielded corresponding products. Significant advantages of this sonochemical synthetic protocol with regard to the conventional thermal methods include easy reaction setup and work-up steps, reasonably mild conditions, shorter reaction times (∼30 min) and comparably high product yields. The characterization of the synthesized compounds was based on melting points, FT-IR, GC-MS, 1H-NMR techniques, and the obtained data were also checked from the previously published studies.