Dearomative (3 + 2) Cycloadditions of Unprotected Indoles
Bram Ryckaert, Jan Hullaert, Kristof Van Hecke, Johan M. Winne
Abstract
The (3 + 2) cycloaddition of various indoles with a dithioallyl cation affords dearomatized cyclopentannulated adducts, with complete control of regioselectivity and excellent chemo- and diastereoselectivity. The success of the reaction critically relies on the use of an excess of very strong Brønsted acid, which paradoxically prevents carbocationic side reactions. The reaction tolerates sensitive functionalities such as basic amines or free hydroxyls, and we demonstrate its use in late stage derivatization of highly functionalized, unprotected indoles.
Topics & Concepts
ChemistryRegioselectivityDerivatizationCycloadditionBrønsted–Lowry acid–base theoryAdductCombinatorial chemistryReaction conditionsOrganic chemistryCatalysisHigh-performance liquid chromatographyAsymmetric Synthesis and CatalysisCatalytic C–H Functionalization MethodsSynthesis and Catalytic Reactions