Transition-metal-switchable divergent synthesis of nitrile-containing pyrazolo[1,5-a]pyridines and indolizines

Palladium-catalyzed oxidative formal [4 + 1] annulation of pyridine-substituted acrylonitriles toward divergent fused N-heterocycles synthesis is reported. The heterodifunctionalization reaction with Cu(OAc)(2) and urea as the nitrogen source accesses to nitrile-substituted pyrazolo[1,5-a]pyridines in moderate to good yields, while the homodifunctionalization reaction with FeBr3 leads to synthesis of nitrilesubstituted indolizines in excellent yields. (C) 2021 Published by Elsevier B.V. on behalf of Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences.

Automated summary

A palladium-catalyzed oxidative formal [4 + 1] annulation of pyridine-substituted acrylonitriles towards divergent fused N-heterocycles synthesis is reported. Heterodifunctionalization with Cu(OAc)(2) and urea gives nitrile-substituted pyrazolo[1,5-a]pyridines in moderate to good yields, while homodifunctionalization with FeBr3 leads to synthesis of nitrile-substituted indolizines in excellent yields.