Stobbe condensation of 3-alkyl- or aryl-4-formylpyrazoles 3a-f with diethyl succinate in the presence of potassium t-butoxide, followed by intramolecular ring closure (Ac2O-NaOAc), afforded the corresponding indazole derivatives 5a-f in 65-85% overall yield. These compounds are good starting materials for transformation to biologically active molecules, such as new pyrazole analogs of the left-hand segment of the potent natural antineoplastic agent CC-1065.
3-烷基或芳基-4-甲酰基
吡唑 3a-f 与
二乙基梯酸在存在叔丁氧化
钾的条件下进行 Stobbe 冷凝反应,随后通过分子内环合(Ac2O-NaOAc)生成相应的
吲哚-并
噁唑衍
生物 5a-f,整体产率为 65-85%。这些化合物是转化为
生物活性分子的良好起始材料,例如强效天然抗肿瘤剂 CC-1065 左侧片段的新
吡唑类似物。