Absolute Configuration of In Situ Crystallized (+)-γ-Decalactone

• Main Authors: Michael Patzer, Nils Nöthling, Richard Goddard, Christian W. Lehmann
• Format: Article
• Language: English
• Published: MDPI AG 2021-04-01
• Series: Chemistry
• Subjects: γ-(+)-decalactone; absolute configuration; in situ cryo-crystallization; flavoring agent; lactone; hydrogen bonding
• Online Access: https://www.mdpi.com/2624-8549/3/2/40

Knowledge about the absolute configuration of small bioactive organic molecules is essential in pharmaceutical research because enantiomers can exhibit considerably different effects on living organisms. X-ray crystallography enables chemists to determine the absolute configuration of an enantiopure compound due to anomalous dispersion. Here, we present the determination of the absolute configuration of the flavoring agent (+)-γ-decalactone, which is liquid under ambient conditions. Single crystals were grown from the liquid in a glass capillary by in situ cryo-crystallization. Diffraction data collection was performed using Cu-Kα radiation. The absolute configuration was confirmed. The molecule consists of a linear aliphatic non-polar backbone and a polar lactone head. In the solid state, layers of polar and non-polar sections of the molecule alternating along the c-axis of the unit cell are observed. In favorable cases, this method of absolute configuration determination of pure liquid (bioactive) agents or liquid products from asymmetric catalysis is a convenient alternative to conventional methods of absolute structure determination, such as optical rotatory dispersion, vibrational circular dichroism, ultraviolet-visible spectroscopy, use of chiral shift reagents in proton NMR and Coulomb explosion imaging.