Thiocarboxamidocinnamonitrile derivatives 2 under bar a-f reacted with 3-aminopyrazole derivative 3 under bar a-c to give the pyrazole[3, 2-b]pyrimidine derivatives 6 under bar a-p. Compounds 6 under bar a-p were used as starting material for syntheses of several heterocylic coompounds. Dehydrogenation of 6 under bar gave pyrazole[3, 2-b]pyrimidines 10 under bar a-d while its reaction with diethyl oxalate gave 11 under bar. Reactions of 6 under bar with formic acid gave pyrazolopyrimidines 17 under bar a-j, and pyrazolopyrimidopyrimidines 18 under bar a-j.