Macrocycle Size Matters: 'Small' Functionalized Rotaxanes in Excellent Yield Using the CuAAC Active Template Approach

摘要

The conceptually novel active template (AT) approach to mechanically interlocked molecules recently introduced by Leigh and co-workers relies on a catalytically active metal center, bound within the cavity of macrocycle, which mediates the formation of a new covalent bond through the ring. Much as the development of passive template methods over the last three decades has allowed the realization of increasingly complex interlocked molecular architectures as well as prototypical molecular machines such as switches, motors, and ratchets, the AT approach has the potential to significantly increase the diversity of synthetically accessible interlocked structures. The AT approach is particularly synthetically powerful as, in principle, any metal-mediated bond formation can be adapted for use in the key bond forming step. Indeed in the six years since the first AT reaction was reported, based on the Sharpless-Huisgen-Meldal-Fokin copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction, the concept has been extended to nine other metal-mediated bond forming reactions, and applied to the synthesis of molecular shuttles, catenanes, and molecules with multiple mechanical bonds.