Catalyst- and Additive-Free Annulation of Ynediones and (Iso)Quinoline <i>N</i>-Oxides: An Approach to Synthesis of Pyrrolo[2,1-<i>a</i>]Isoquinolines and Pyrrolo[1,2-<i>a</i>]Quinolines
Wan-Wan Yang, Ya-Fang Ye, Lulu Chen, Ji‐Ya Fu, Junyan Zhu, Yan‐Bo Wang
Abstract
A simple and effective annulation of ynediones and (iso)quinoline N-oxides was developed to afford various functionalized pyrrolo[2,1-a]isoquinolines and pyrrolo[1,2-a]quinolines in moderate to excellent yields. This protocol underwent a tandem [3 + 2] cycloaddition/ring-opening/N-nucleophilic addition, which exhibited high regioselectivity, broad substrate tolerance, and atom economy under catalyst-, additive-free, and air conditions. Moreover, indolizine was also successfully prepared using pyridine N-oxide.
Topics & Concepts
ChemistryAnnulationQuinolineCycloadditionRegioselectivityIndolizineCatalysisRing (chemistry)Atom economyPyridineCombinatorial chemistrySubstrate (aquarium)Medicinal chemistryNucleophileOrganic chemistryGeologyOceanographyCyclopropane Reaction MechanismsSynthesis and Characterization of PyrrolesSynthesis and Reactivity of Heterocycles