Back to basics: A transition‐metal‐free method developed for the synthesis of indazoles involves an inexpensive catalytic system composed of a diamine and K2CO3. Various (Z)‐2‐bromoacetophenone tosylhydrazones were converted into indazoles at room temperature in excellent yields (see example; Ts=p‐toluenesulfonyl). The yield was improved by photoisomerization with UV light when E/Z isomeric mixtures
简而言之:为合成吲唑而开发的一种无过渡金属的方法涉及由二胺和K 2 CO 3组成的廉价催化体系。各种(Z)-2-溴苯乙酮甲苯磺酰hydr在室温下均以优异的收率转化为吲唑(请参见示例; Ts =对甲苯磺酰基)。当使用原料的E / Z异构体混合物时,通过UV光进行光致异构化提高了产率。