Organocatalytic Formal (3 + 2) Cycloaddition toward Chiral Pyrrolo[1,2-<i>a</i>]indoles via Dynamic Kinetic Resolution of Allene Intermediates
Jian‐Fei Bai, Lulu Zhao, Fang Wang, Fachao Yan, Taichi Kano, Keiji Maruoka, Yuehui Li
Abstract
We report the chiral phosphoric acid catalyzed formal (3 + 2) cycloaddition of 3-substituted 1H-indoles and propargylic alcohols containing a functional directing group (p-NHAc or p-OH). This work represents a straightforward method to synthesize chiral pyrrolo[1,2-a]indole bearing a tetrasubstituted carbon stereocenter. The reaction proceeds smoothly with a wide array of substrate tolerance to deliver various chiral pyrrolo[1,2-a]indoles in up to 93% yield and 98% ee. The utility of this method is highlighted by the diverse transformations of the products into various indole derivatives.
Topics & Concepts
StereocenterAlleneChemistryCycloadditionKinetic resolutionIndole testYield (engineering)Substrate (aquarium)Combinatorial chemistryOrganocatalysisFunctional groupEnantioselective synthesisPhosphoric acidCatalysisStereochemistryOrganic chemistryGeologyMaterials scienceMetallurgyPolymerOceanographySynthesis of Indole DerivativesCatalytic C–H Functionalization MethodsSynthesis and Characterization of Pyrroles