Synthesis of Cryptophane-B: Crystal Structure and Study of Its Complex with Xenon

Whereas the synthesis of the $anti$-cryptophane-A (1) derivative is known for nearly 40 years, the preparation of its diastereomer (cryptophane-B according to Collet's nomenclature) has never been reported. Thus, the synthesis of the cryptophane-B derivative represents a real challenge for chemists interested in the preparation of these hollow molecules. Herein, we describe a synthetic route that allows us to prepare cryptophane-B (2), however in low yield. The X-ray crystallographic structure of this compound is described and it reveals the presence of an ethanol molecule inside the cavity of the host. Finally, the ability of cryptophane-B to bind xenon in 1,1,2,2-tetrachloroethane-$d_2$ is also studied via hyperpolarized $^{129}$Xe NMR