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.

中文翻译：

---

实用的合成1-取代的5-氨基吡唑并[4,3-

分子内Friedel-Crafts型环化是合成稠合双环嘧啶酮的有效方法。但是，尚未实现使用这种环化方法合成1-取代的吡唑并[4，3 - d ]嘧啶-7-酮。在这里，我们描述了使用实际的分子内Friedel-Crafts型环化反应在N ，N-二甲基甲酰胺中存在三甲基氯硅烷的情况下合成各种1-取代的吡唑并[4,3 - d ]嘧啶-7-酮的方法。通过该方法有效地合成了缺氧诱导因子脯氨酰羟化酶结构域（HIF-PHD）抑制剂。