Crystal structures of anhydrous and hydrated N-benzyl-cinchonidinium bromide

Daron E Janzen; Maya S Butler; Eric W Reinheimer

doi:10.1107/S2056989022005096

Crystal structures of anhydrous and hydrated N-benzyl-cinchonidinium bromide

Acta Crystallogr E Crystallogr Commun. 2022 May 17;78(Pt 6):594-598. doi: 10.1107/S2056989022005096. eCollection 2022 Jun 1.

Authors

Daron E Janzen¹, Maya S Butler¹, Eric W Reinheimer²

Affiliations

¹ Dept. of Chemistry & Biochemistry, St. Catherine University, 2004 Randolph Avenue, St. Paul, MN 55105, USA.
² Rigaku Americas Corporation, 9009 New Trails Drive, The Woodlands, TX 77381, USA.

Abstract

N-benzyl-cinchonidinium bromide, C₂₆H₂₉N₂O⁺·Br^-, with the systematic name (R)-[(2S,4S,5R)-1-benzyl-5-ethenyl-1-azoniabi-cyclo-[2.2.2]octan-2-yl](quinolin-4-yl)-methanol bromide, is a quaternary ammonium salt of the cinchona alkaloid cinchonidine. This salt is widely used as a chiral phase-transfer catalyst and chiral resolution agent. Both classical and non-classical hydrogen-bonding inter-actions, as well as anion effects have been shown to play key mechanistic roles in the catalysis of cinchona alkaloids. In an effort to understand the effects of water on these inter-molecular inter-actions, the structures of anhydrous N-benzyl-cinchonidinium bromide, (I), and the sesquihydrate, C₂₆H₂₉N₂O⁺·Br^-·1.5H₂O, (II), were determined.

Keywords: crystal structure; hydrogen bonding; quaternary ammonium salt of cinchonidine.

Grants and funding

Funding for this research was provided by: National Science Foundation, Major Research Instrumentation Program (award No. 1125975 to St. Catherine University); St. Catherine University, Collaborative Undergraduate Research Program, Summer Scholars (grant to D. Janzen, M. Butler).