Optical Resolution of Rimantadine

This work discloses a new procedure for the resolution of commercially available racemic rimantadine hydrochloride to enantiomerically pure (S)-rimantadine using (R)-phenoxypropionic acid as a recyclable resolving reagent. Good chemical yields, operational ease, and low-cost structure underscore the preparative value of this method for the production of enantiomerically pure rimantadine for medicinal or synthetic studies.

Crystal Structure Explains Crystal Habit for the Antiviral Drug Rimantadine Hydrochloride

The crystal structure of the antiviral drug rimantadine hydrochloride, C12H22N+ Cl−, has been elucidated by a single-crystal X-ray structure analysis. The structure consists of 1-(1- adamantyl)ethanamine (rimantadinium) cations and chloride anions. The Cl− anions link the rimantadinium cations via N-H...Cl hydrogen bonds into infinite rectangular chord-like structural units with charged groups in the inner channel and aliphatic groups on the surface, and oriented along the unit cell c axis. In contrast to strong electrostatic and hydrogen bonding inner interactions the chords in the crystal are held together by weak van der Waals forces only. A two-fold symmetry axis passes through the center of the chord. By indexing of the crystal faces it has been shown that the maximal dimension of the needle-like crystals coincides with the direction of the unit cell c axis. These structural features explain the crystal habit and the anisotropy of the mechanical properties of rimantadine hydrochloride crystals observed upon slicing and cleavage.