Improbable Rotaxanes Constructed From Surrogate Malonate Rotaxanes as Encircled Methylene Synthons.

We have developed a new approach for the synthesis of "improbable" rotaxanes by using malonate-centered rotaxanes as interlocked surrogate precursors. Here, the desired dumbbell-shaped structure can be assembled from two different, completely separate, portions, with the only residual structure introduced from the malonate surrogate being a methylene group. We have synthesized improbable [2]- and [3]rotaxanes with all-hydrocarbon dumbbell-shaped components to demonstrate the potential structural flexibility and scope of the guest species that can be interlocked when using this approach.

Dual-Way-Switchable Ester Rotaxanes Constructed Using the Recognition of Malonate Diesters.

Malonate diesters can thread into the cavity of a di(ethylene glycol)-containing macrocycle under the templating effect of a Na ion; the corresponding rotaxanes can be synthesized with good efficiency by applying several stoppering reactions. A molecular switch, in which the interlocked macrocycle was moved between two rarely used stations (i.e.