Magic ring catenation by olefin metathesis

(Chemical Equation Presented) Olefin metathesis has been employed in the efficient syntheses of a [2]catenane with the temptation being provided by the recognition between a secondary ammonium ion and a crown ether. In one approach, a crown ether precursor has been clipped around an NH₂⁺ center situated in a macrocyclic ring, yielding the mechanically interlocked compound. In the other approach, the reversible nature of olefin metathesis allows for a magic ring synthesis to occur wherein two free macrocycles can be employed as the stationary materials, leading to the formation of the same [2]catenane.