An Assembly of Pyrano[3,2‐<i>b</i>]indol‐2‐ones via <scp>NHC‐Catalyzed</scp> [3 + 3] Annulation of Indolin‐3‐ones with Ynals<sup>†</sup>
Xia Wang, Shulei Zhang, Shaojie Wang, Hao An, Xiaolan Xin, Haonan Lin, Zhifeng Tu, Shenci Lu
Abstract
Comprehensive Summary We report herein an unprecedented N ‐heterocyclic carbene‐catalyzed formal [3 + 3] annulation of ynals with N ‐Ts indolin‐3‐ones under the oxidation condition affording the functionalized pyrano[3,2‐ b ]indol‐2‐ones. The alkynyl acylazoliums via the combination of a carbene with ynals in the presence of oxidate proved to be the important intermediates for the success of this transformation. This method features a broad substrate scope and mild conditions, including axially chiral skeletons with suitable substitutions.
Topics & Concepts
AnnulationChemistryCarbeneCatalysisCombinatorial chemistrySubstrate (aquarium)Scope (computer science)Medicinal chemistryStereochemistryOrganic chemistryGeologyOceanographyProgramming languageComputer scienceN-Heterocyclic Carbenes in Organic and Inorganic ChemistryCatalytic C–H Functionalization MethodsCyclopropane Reaction Mechanisms