Synthesis of Diversified Pyrazolo[3,4-b]pyridine Frameworks from 5-Aminopyrazoles and Alkynyl Aldehydes via Switchable C≡C Bond Activation Approaches
Xiaoyu Miao, Yong-Ji Hu, Fu-Rao Liu, Yuanyuan Sun, Die Sun, An‐Xin Wu, Yanping Zhu
Abstract
A cascade 6-endo-dig cyclization reaction was developed for the switchable synthesis of halogen and non-halogen-functionalized pyrazolo[3,4-b]pyridines from 5-aminopyrazoles and alkynyl aldehydes via C≡C bond activation with silver, iodine, or NBS. In addition to its wide substrate scope, the reaction showed good functional group tolerance as well as excellent regional selectivity. This new protocol manipulated three natural products, and the arylation, alkynylation, alkenylation, and selenization of iodine-functionalized products. These reactions demonstrated the potential applications of this new method.
Topics & Concepts
ChemistryHalogenSubstrate (aquarium)IodinePyridineFunctional groupCombinatorial chemistryHalogen bondMedicinal chemistryOrganic chemistryGeologyPolymerOceanographyAlkylCatalytic C–H Functionalization MethodsCatalytic Alkyne ReactionsSulfur-Based Synthesis Techniques