Synthesis of 7-substituted pyrazolo[1,5-a]pyrimidine-3-carboxamides as potential non benzodiazepine hypnotics

Abstract

A variety of new pyrazolo[1,5-a]pyrimidines has been prepared as potential drugs for the treatment of insomnia. The general synthetic route used for this purpose involves the condensation of substituted cyanoacetamides 5a-c, prepared by reaction of cyanoacetic acid with amines in presence of acetic anhydride, with dimethylformamide dimethylacetal and subsequent treatment of the formed enamines 6 with hydrazine hydrate. This process affords the corresponding aminopyrazole carboxamides 9 that react with the enaminonitrile 12 to generate the targets. Structures of the substance prepared in these sequences were established by using spectroscopic methods, including 15N HMBC and NOE difference experiments, as well as X-raycrystallographic analysis.