Synthesis of pyrazolopyrimidinones as sildenafil derivatives and sclerotigenin

A series of novel pyrazolo pyrimidinone derivatives (3(a–d), 4(a–d), and 6(a–d)) was synthesized from various pyrazolo amides (2a–d) which are synthesized by the reaction between ethyl 5-amino-3-methyl-1-phenyl-1H-pyrazole-4-carboxylate (1) and various lithium amides. In addition, we also described the synthesis of sclerotigenin drug molecule which has quinazoline moiety from simple 2-nitro benzoic acid with high yields.