Visible‐Light Mediated One‐Pot Synthesis of Pyrazolo[3,4‐ b ]Pyridines via Intramolecular Rearrangement

An unprecedented one‐pot, visible‐light mediated method for the construction of pyrazolo[3,4‐ b ]pyridine frameworks from 5‐amino‐1 H ‐pyrazole‐4‐carbaldehydes and enaminones via intramolecular rearrangement is unveiled employing LED light and potassium persulfate. This protocol allows a convenient route to achieve the desired products with wide substrate scope, short route, gram‐scale synthesis and enabling biologically relevant pyrazolopyrimidine scaffolds in good yields. Further, the mechanistic pathway of the reaction was elucidated via prime energy calculations using Force Field OPLS 4. In addition, the intermediates were also trapped and investigated through NMR experiment and confirmed the structures by X‐ray analysis.