Synthesis of a Double-Spanned Resorc[4]arene via Ring-Closing Metathesis and Calculation of Aggregation Propensity

Ring-closing metathesis (RCM) catalyzed by the second-generation Grubbs catalyst has been used to synthesize resorc[4]arenes 2b–5b starting from undecenyl resorc[4]arene 1b fixed in the cone conformation. X-ray diffraction analysis revealed for the major metathesis product 3b (50% yield) a cavity-shaped architecture resembling a basket, endowed with a large (≈ 10 Å) intramolecular space, and a strong propensity to self-assembly as a supramolecular trio of heterochiral dimers. This prompted us to investigate the aggregation propensity of basket 3b also in THF/water solution by UV-visible spectroscopy. Cavitation Gibbs free energy change (NNGcav = 4.78 kcal mol–1) associated with the self-assembly of macrocycle 3b was calculated as a measure of the solvophobic interactions involved in the process.