Synthesis and X-ray structure of amide-based macrocycles, catenanes and pretzelane

The syntheses and crystal structure studies of amide-based catenanes derive d from m-phenylene diacrylic acid and 5-acetoxy isophthalic acid (17% and 3 % yield of 4a and 4b resp.) and octalactam macrocycles (21% yield of 3) are described. Hydrogen bonding patterns play a key role in the formation of t he different conformations of octalactam 3. The crystal structures of 3 rev eal a number of hydrogen-bonding interactions between the macrocycle and tw o different solvent molecules, which are presumably responsible for the dif ferent conformations. Furthermore, we report the X-ray structure of a caten ane, which was converted into a "pretzelane" by bridging two phenolic hydro xy groups with a p-xylylene unit.