Racemic and Meso Crystal Structures of an Axial-Chiral Spirobi-(dinaphthoazepin)ium Salt: Emergence of an S4-Symmetric Molecule

Honegger, Philipp; Gajic, Natalie; Prado-Roller, Alexander; Widhalm, Michael

doi:10.3390/sym13081365

Open AccessArticle

Racemic and Meso Crystal Structures of an Axial-Chiral Spirobi-(dinaphthoazepin)ium Salt: Emergence of an S₄-Symmetric Molecule

¹

Institute of Computational Biological Chemistry, University of Vienna, Währinger Straße 17, 1090 Vienna, Austria

²

Institute of Inorganic Chemistry, University of Vienna, Währinger Straße 42, 1090 Vienna, Austria

³

Institute of Chemical Catalysis, University of Vienna, Währinger Straße 38, 1090 Vienna, Austria

^*

Author to whom correspondence should be addressed.

Symmetry 2021, 13(8), 1365; https://doi.org/10.3390/sym13081365

Submission received: 9 July 2021 / Revised: 26 July 2021 / Accepted: 26 July 2021 / Published: 27 July 2021

(This article belongs to the Special Issue Asymmetry and Symmetry in Organic Chemistry 2021)

Download

Browse Figures

Versions Notes

Abstract

To date, only a few instances of S₄-symmetric organic molecules exist. In principle, spirobi-(dinaphthoazepin)ium cations can achieve this highly symmetric point group. Heating racemic 2,2′-bis(bromomethyl)-1,1′binaphthyl with aqueous ammonia afforded a mixture of rac- and meso-3,3′,5,5′-tetrahydro-4,4′-spirobi[dinaphtho[2,1-c:1′,2′-e]azepin]-4-ium bromide which was separated by fractional crystallisation. Both stereoisomers were characterised spectroscopically, and their crystal structures were determined and compared. The rac crystal structure differs significantly from the known enantiopure one. The meso molecules display a near-perfect S₄ symmetry. Upon treatment with KO^tBu, both isomers undergo Stevens rearrangement.

Keywords: crystal structure; three-dimensional structure; chirality; axial chirality; racemate; meso; spiro compound; Stevens rearrangement

Share and Cite

MDPI and ACS Style

Honegger, P.; Gajic, N.; Prado-Roller, A.; Widhalm, M. Racemic and Meso Crystal Structures of an Axial-Chiral Spirobi-(dinaphthoazepin)ium Salt: Emergence of an S₄-Symmetric Molecule. Symmetry 2021, 13, 1365. https://doi.org/10.3390/sym13081365

AMA Style

Honegger P, Gajic N, Prado-Roller A, Widhalm M. Racemic and Meso Crystal Structures of an Axial-Chiral Spirobi-(dinaphthoazepin)ium Salt: Emergence of an S₄-Symmetric Molecule. Symmetry. 2021; 13(8):1365. https://doi.org/10.3390/sym13081365

Chicago/Turabian Style

Honegger, Philipp, Natalie Gajic, Alexander Prado-Roller, and Michael Widhalm. 2021. "Racemic and Meso Crystal Structures of an Axial-Chiral Spirobi-(dinaphthoazepin)ium Salt: Emergence of an S₄-Symmetric Molecule" Symmetry 13, no. 8: 1365. https://doi.org/10.3390/sym13081365

APA Style

Honegger, P., Gajic, N., Prado-Roller, A., & Widhalm, M. (2021). Racemic and Meso Crystal Structures of an Axial-Chiral Spirobi-(dinaphthoazepin)ium Salt: Emergence of an S₄-Symmetric Molecule. Symmetry, 13(8), 1365. https://doi.org/10.3390/sym13081365

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Menu

Racemic and Meso Crystal Structures of an Axial-Chiral Spirobi-(dinaphthoazepin)ium Salt: Emergence of an S₄-Symmetric Molecule

Abstract

Share and Cite

Article Metrics

Article Access Statistics

Further Information

Guidelines

MDPI Initiatives

Follow MDPI