Clockwise–counterclockwise differentiation on the upper rim of a monofunctional γ-cyclodextrin: efficient topological control in the syntheses of capped cyclodextrins

Intramolecular condensation of 6(A)-(N-dansyl-l-cysteine)-gamma-cyclodextrin occurred only at 6(B)-OH of the many OH groups to afford the corresponding lactone with an exo-topology.