An efficient and simple method for the synthesis of pyrazolo[3,4-a]acridine and pyrazolo[4,3-a]acridine derivatives directly form nitro compounds by in situ reduction and cyclization reaction under Fe/H2O medium is reported. Compared to amino compounds, nitro compounds are more stable and easier to obtain. In addition, because iron is a nontoxic, inexpensive, and environmentally friendly reductant, this method is especially suitable for organic synthesis. The other advantages of this process are cheap raw materials, less pollution, and wide substrate range.
