PRACTICAL SYNTHESIS OF 1-SUBSTITUTED 5-AMINOPYRAZOLO[4,3-d]PYRIMIDIN-7-ONES USING INTRAMOLECULAR FRIEDEL-CRAFTS TYPE CYCLIZATION AND ITS APPLICATION TO THE SYNTHESIS OF PHARMACEUTICALLY ACTIVE COMPOUNDS

摘要

Intramolecular Friedel-Crafts type cyclization is known as an efficient method of synthesizing fused bicyclic pyrimidones.However,the synthesis of 1-substituted pyrazolo[4,3-d]pyrimidin-7-ones using this cyclization method has not been achieved.Herein,we describe the synthesis of various 1-substituted pyrazolo[4,3-d]pyrimidin-7-ones using practical intramolecular Friedel-Crafts type cyclization,which was carried out in N,N-dimethylformamide in the presence of chlorotrimethylsilane.A hypoxia-inducible factor prolyl hydroxylase domain(HIF-PHD)inhibitor was efficiently synthesized by this method.