General method for synthesis of functionalized macrocycles and catenanes utilizing "click" chemistry

A new protocol for efficient and high yield synthesis of functionalized macrocycles and catenanes has been developed using "click" chemistry in combination with Sauvage's metal template route to interlocked structures. The procedure involves introduction of terminal alkyne moieties on a symmetrical 2,9-diaryl-1,10-phenanthroline (phen) building block, followed by double-"click" ring closure using aryl 3,5-diazides in the presence of CuI, sodium ascorbate, the base DBU and a sulfonated phenanthroline ligand in an oxygen-free 7:3:1 ethanol/water/toluene mixture at 70 degrees C. Utilizing acetal and vinyl substituted diazides, the corresponding bistriazole/phen macrocycles, characterized spectroscopically, were obtained in 65-70% yield. Formation of a binary Cu(I) complex of the diethynylphen ligand followed by reaction with aryl 3,5-diazides using a modified procedure affords the corresponding difunctionalized catenane in one step in 85-92% yield. The initial catenanes obtained after workup are Cu-free. Reintroduction of Cu(I) using Cu(CH3CN)4+PF6- gives the metallocatenanes, whose spectral properties are identical to those of related (phen)2Cu(I) catenanes reported by Sauvage and co-workers. This methodology provides ready access to functionalized interlocked structures, which can be used as intermediates in the preparation of a variety of new materials, including compounds of interest as artificial photosynthetic systems.