Formation of copper(I)-templated [2]rotaxanes using “click” methodology: influence of the base, the thread and the catalyst

Abstract : Three new copper(I)-assembled [2]rotaxanes incorporating the same macrocycle and different axes containing a bipy, a phen or a terpy have been synthesized thanks to CuAAC reaction for attaching the stoppers. The influence of the nature of the base used for the stoppering reaction was investigated on the formation of the bipy-containing rotaxane. The yield of the [2]rotaxane synthesis was increased when using a phen as a coordinating unit in the thread with [Cu(CH3CN)4](PF6) as catalyst. The strong influence of the nature of the catalyst was clearly evidenced for the formation of the terpy rotaxane, increasing the yield of the stoppering reaction from 0 to 95% by just substituting the Cu(I) catalyst. Finally, the best conditions found for our systems are the use of Na2CO3 as a base and Cu(tren′)Br as a catalyst.