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

Whereas
the synthesis of the anti-cryptophane-A
(1) derivative has been 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), albeit in a 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-d2 is also studied via hyperpolarized 129Xe NMR.