Silver-Promoted (4 + 1) Annulation of Isocyanoacetates with Alkylpyridinium Salts: Divergent Regioselective Synthesis of 1,2-Disubstituted Indolizines
Yan Chen, Andrey Shatskiy, Jian‐Quan Liu, Markus D. Kärkäs, Xiang‐Shan Wang
Abstract
An unprecedented silver-promoted regioselective (4 + 1) annulation of isocyanoacetates with pyridinium salts is reported. The established protocol provides controlled, facile, and modular access to a range of synthetically useful N-fused heterocyclic scaffolds containing indolizines, pyrrolo[1,2-a]quinolines, pyrrolo[2,1-a]isoquinolines, and 1H-imidazo[4,5-a]indolizin-2(3H)-ones. A mechanistic pathway involving nucleophilic addition/protonation/elimination/cycloisomerization is proposed.
Topics & Concepts
ChemistryRegioselectivityPyridiniumAnnulationCycloisomerizationNucleophileProtonationCombinatorial chemistryMedicinal chemistryOrganic chemistryCatalysisIonSynthesis and Reactivity of HeterocyclesCyclopropane Reaction MechanismsSynthesis and Characterization of Pyrroles