https://www.selleckchem.com/pr....oducts/importazole.h
Two diastereomeric crystalline steroid dimers were obtained by acid catalyzed double acetalization of (20S)-5α-pregnan-3β,16β,20-triol 3-monoacetate with terephtalaldehyde. These compounds were characterized by NMR in solution, MS, Single Crystal X-ray Diffraction and variable temperature solid-state NMR by 13C CPMAS. While the phenylene rotator in the SR diastereomer remains static even at 373 K, the RR isomer shows a slow rotational process of the phenylene ring at temperatures above room temperature and thus may be considered the