Metal‐Free Active Template Synthesis of Catenanes

We report a strategy for catenane synthesis that does not require persistent strong binding interactions on the components nor the addition of templates. The kinetically controlled process features the condensation of a diamine and a p-nitrophenol diester accelerated through the cavity of a crown ether. Amidation first generates a linear monoamide bearing an amine at one terminus of the chain and a p-nitrophenol ester at the other. This intermediate undergoes macrocyclization via a second amidation reaction through the crown ether cavity, resulting in interlocked macrocycles. Carrying out a similar macrocyclization reaction via ring-closing alkene metathesis (which is not accelerated through the crown ether cavity) affords macrocycle but no catenane, demonstrating that the metal-free active template synthesis enables the synthesis of catenanes despite the absence of strong intercomponent binding. A series of catenanes were synthesized in yields of up to 77%. X-Ray crystallography shows networks of weak intercomponent amide–ether hydrogen bonds in the catenanes, a rarely observed interaction adopted as a result of mechanical interlocking trapping the functional groups in close proximity.