N-Heterocyclic Carbene-Catalyzed [3+3] Annulation of 5-Aminopyrazoles with Enals: Enantioselective Synthesis of Pyrazolo[3,4-b]pyridones

An enantioselective construction of pyrazolo-[3,4-b]-pyridones was achieved via N-heterocyclic carbene-catalyzed [3 + 3] annulation of enals with 5-aminopyrazoles. This protocol not only offers a highly efficient synthetic approach for the preparation of various substituted pyrazolo-[3,4-b]-pyridones but also provides an effective method for the rapid synthesis of enantiopure spirooxindone derivatives.

Automated summary

An enantioselective construction of pyrazolo-[3,4-b]-pyridones was achieved via N-heterocyclic carbene-catalyzed [3 + 3] annulation of enals with 5-aminopyrazoles. This protocol provides a highly efficient synthetic approach for the preparation of various substituted pyrazolo-[3,4-b]-pyridones and an effective method for the rapid synthesis of enantiopure spirooxindone derivatives.