Coupling Reaction of 2-Hydroxyindoline with Arenes by BF₃·Et₂O. A Convenient Synthetic Method of Isolable Diastereomeric Atropisomers

Abstract

A simple method for synthesis of 2-aryl-substituted 3, 3-dimethylindoline derivatives was established by the reaction of 1-acyl-2-hydroxy-3, 3-dimethylindoline with electron-rich arenes in the presence of boron trifluoride-diethly ether in dioxane. In the reaction with β-naphthol, a pair of isolable diastereomeric atropisomers was isolated. The conformations of both atropisomers were determined by single crystal X-ray analyses. The substitution reaction behavior toward various arenes was accounted for in terms of frontier molecular orbital (FMO) theory.