Quaternization of Aromatic Amines Menschutkin Reaction

In the early 1980s, Stoddart and coworkers investigated the complexation of pyr-idinium dications (e.g., paraquat) using crown ethers [12]. The complexation of 

A representative selection of [2]catenanes synthesized by this route is given in Table 10.1[14b, 15a, 16]. It is remarkable to note that the first [2]catenane synthesized (entry 2, Table 10.1) could be isolated in 74% yield [14,16], The final entry in the table is an example of an expanded version of the tetracationic macrocycle which incorporates a biphenylene spacer between the paraquat residues and can accommodate two n-stacked aryl rings within its cavity. The reaction results in the isolation of the [3]catenane product in 25% yield with very little (2%) [2]catenane isolated [16p]. A spectacular demonstration of the power of this approach by Stoddart and coworkers was the iterative synthesis of a [5] catenane which the authors dubbed Olympiadane after its resemblance to the Olympic rings [17]. 

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