Structural parameters governing the dynamic combinatorial synthesis of catenanes in water.

We report the first dynamic combinatorial synthesis in water of an all-acceptor [2]catenane and of different types of donor-acceptor [2] and [3]catenanes. Linking two electron-deficient motifs within one building block using a series of homologous alkyl chains provides efficient and selective access to a variety of catenanes and offers an unprecedented opportunity to explore the parameters that govern their synthesis in water. In this series, catenane assembly is controlled by a fine balance between kinetics and thermodynamics and subtle variations in the building block structure, such as the linker length and building block chirality. A remarkable and unexpected odd-even effect with respect to the number of atoms in the alkyl linker is reported.