Three-Component Fusion to Pyrazolo[5,1-a]isoquinolines via Rh- Catalyzed Multiple Order Transformation of Enaminones

A facile and practical method for the synthesis of fused tricyclic pyrazolo[5,1-a]isoquinolines has been realized via the reactions of enaminones, hydrazine hydrochloride, and internal alkynes. By means of Rh catalysis, the extraordinary high-order bond functionalization, including the transformation of aryl C-H, ketone C=O, and alkenyl C-N bonds in the enaminones, marks the major feature of the cascade reactions. The results disclose the individual advantage of enaminones in the design of novel and efficient synthetic methods.

Automated summary

A facile and practical method for the synthesis of fused tricyclic pyrazolo[5,1-a]isoquinolines has been developed via the reactions of enaminones, hydrazine hydrochloride, and internal alkynes using Rh catalysis. The cascade reactions demonstrate the remarkable high-order bond functionalization, involving the transformation of aryl C-H, ketone C=O, and alkenyl C-N bonds in the enaminones. This study highlights the individual advantage of enaminones in the design of novel and efficient synthetic methods.