No abstract

Catenanes composed of two achiral rings that are oriented (C nh symmetry) because of the sequence of atoms they contain are referred to as topologically chiral. Here, we present the synthesis of a highly enantioenriched catenane containing a related but overlooked “co-conformationally ‘topologically’ chiral” stereogenic unit, which arises when a bilaterally symmetric C nv ring is desymmetrized by the position of an oriented macrocycle.

Active-template auxiliary methodologies have previously been developed for the stereoselective synthesis of chiral interlocked molecules in which the mechanical bond provides the sole stereogenic unit. To date however, the covalent auxiliary has been included in the half-axle components (rotaxanes) or pre-macrocycle components (catenanes), and thus mechanically chiral rotaxane and catenane syntheses rely on different chiral components. Here we present a single, simple amino acid-derived macrocycle that mediates the formation of both catenanes and rotaxanes in excellent stereoselectivity. We demonstrate the flexibility of our approach through the stereoselective synthesis of all three isomers of a co-conformationally mechanically planar chiral [3]rotaxane.

As recognized in the early 1960s, catenanes composed of two achiral rings that are oriented (Cnh symmetry) as a result of the sequence of atoms they contain are topologically chiral. Here we present the first synthesis of a highly enantioenriched catenane containing a related but overlooked “co-conformationally ‘topologically’ chiral” stereogenic unit, which arises when a bilaterally symmetric Cnv ring is desymmetrised by the position of an oriented macrocycle.

Active-template auxiliary methodologies have previously been developed for the stereoselective synthesis of chiral interlocked molecules in which the mechanical bond provides the sole stereogenic unit. To date however, the covalent auxiliary has been included in the half-axle components (rotaxanes) or pre-macrocycle components (catenanes), and thus mechanically chiral rotaxane and catenane syntheses rely on different chiral components. Here we present a single, simple amino acid-derived macrocycle that mediates the formation of both catenanes and rotaxanes in excellent stereoselectivity. We demonstrate the flexibility of our approach through the stereoselective synthesis of all three isomers of a co-conformationally mechanically planar chiral [3]rotaxane.