Triphenylphosphonium-stoppered [2]rotaxanes

(equation presented) The template-directed syntheses of two [2]rotaxanes, one carrying one and the other two triphenylphosphonium stoppers, have been achieved using a threading-followed-by-stoppering approach. Either one or two benzylic bromide functions-located at the para-positions of dibenzylammonium-based ions, which become encircled by dibenzo[24]crown-8 macrocycles during the initial thermodynamically controlled phases that mark the recognition events-serve as sites for nucleophilic attack by triphenylphosphine during the subsequent kinetic stages that lead to the formation of the two [2]rotaxanes.