Bambusuril analogs based on alternating glycoluril and xylylene units


                                  Tomáš Lízal,^ Vladimír Šindelář
                                                 ^


Glycoluril is a urea-based heterocyclic molecule, which is a suitable building block for
macrocyclic receptors. These host molecules can interact with cationic, anionic or neutral guests.
Bambusurils^1 are potent anion receptors that were used to detect and quantify anions in a complex
mixture by NMR^2. In order to allow anion sensing by UV-VIS spectroscopy, we designed a new
bambusuril derivative incorporating aromatic groups in its structure.

Here we present synthesis of the new hybrid macrocycles consisting of glycoluril and aromatic
units. Inspired by work of prof. Shimizu^3, we employed basic synthetic conditions which afforded
us with mixture of macrocyclic of various sizes. The macrocyclic homologues were separated by
reverse-phase flash chromatography and characterized by the means of NMR spectroscopy and X-ray
crystallography. The conformational behavior of separated isomers was investigated using DFT models
and variable-temperature NMR.




Figure 1. Xylylene-glycoluril macrocycle.












References

[1] J. Švec, M. Nečas, V. Šindelář, Angew. Chemie Int. Ed. 2010, 49, 2378;

[2] V. Havel, M. A. Yawer, V. Šindelář, Chem. comm. 2015, 51, 4666;

[3] K. Roy, C. Wang, P. J. Pellechia, L. S. Shimizu, J. Org. Chem. 2010, 75, 5453.