Chiral Dendrophanes, Dendro[2]rotaxanes, and Dendro[2]catenanes: Synthesis and Chiroptical Phenomena

Abstract

New chiral dendrimers with planar-chiral, cycloenantiomeric and topologically chiral cores were prepared in yields of up to 90% starting from a racemic 4-hydroxy[2.2]paracyclophane, a [2]rotaxane with sulfonamide groups in the wheel and axle positions and [2]catenane with a sulfonamide group in both of its macrocycles. The separation of the racemic mixture of these dendrimers was possible by HPLC on chiral stationary phases. The CD spectra of the dendro[2.2]phanes showed a hitherto unknown influence of the dendritic part on the intensities of the Cotton effects. The chirality of these dendrimers is dependent not only on its chiral elements but also on its dendritic wedges and their generation.