Asymmetric Synthesis of Indolines through Intramolecular Shifting of Aromatic Sulfinyl Groups. Role of the π,π-Stacking Interactions in these Unusual SNAr Processes

Cyclization of N-aryl substituted 1-aryl-2[2-p-tolylsulfinyl]phenyl propylamines under LDA, LHMDS, or KHMDS provides a new approach for synthesizing optically pure 2,3-disubstituted indolines. Both the scope and the limitations of this method have been investigated. The pi,pi-stacking interactions are crucial for these unprecedented intramolecular SNAr processes, in which a sulfinyl group located on a slightly deactivated ring is substituted by amide anions under mild conditions. X-ray and NMR proofs supporting these pi,pi-stacking interactions are presented.