The Synthesis of New 5-R-aminoazolo[1,5-a]pyrimidin-7-ones from an N,S-acetal Derivative of Meldrum’s Acid

A one-step method for the synthesis of new 5-aminoazolo[1,5-a]pyrimidines was developed. The use of a synthetic equivalent of carbonyl dielectrophile based on Meldrum's acid made it possible to introduce a substituted amino group into position 5 of azolo[1,5-a]-pyrimidines without the use of severe conditions and palladium catalysts. The tolerance of the reaction to various substituents was also investigated. Based on the isolated intermediates, a reaction mechanism of the process was proposed. Moreover, the possibility of synthesizing analogs of biologically active molecules based on the obtained compounds was demonstrated.