Synthesis of enantiopure, trisubstituted cryptophane-A derivatives.

The efficient synthesis of enantiopure, trisubstituted cryptophane-A derivatives, organic host molecules with unusually high xenon affinity, is reported. Synthesis and chromatographic separation of (+/-) tri-Mosher's acid substituted cryptophane diastereomers gave ready access to the enantiopure cryptophanes, which are critical components in the design of enantiomerically pure Xe-129 biosensors. Hyperpolarized Xe-129 NMR spectroscopy identified single resonances for both trisubstituted cryptophane diastereomers that were separated by 9.5 ppm. This highlights opportunities for using enantiopure xenon biosensors in the simultaneous detection of Xe-129 in different biochemical environments.