Interesting ChemistryAbsolute ConfigurationBiochemistryBulk SolutionsChemical TransformationsChemical Sciences

Organocatalytic cyclopropanation of an enal: (computational) assignment of absolute configurations.

https://doi.org/10.59350/nnskj-c0264
Published in Henry Rzepa's Blog

I am exploring the fascinating diverse facets of a recently published laboratory experiment for undergraduate students.[cite]10.1021/acs.jchemed.7b00566[/cite] Previously I looked at a possible mechanistic route for the reaction between an enal (a conjugated aldehyde-alkene) and benzyl chloride catalysed by base and a chiral amine, followed by the use of NMR coupling constants to assign relative stereochemistries.

References

Physical and Theoretical ChemistryGeneral Physics and Astronomy

The Absolute Configuration of Optically Active Molecules

https://doi.org/10.1063/1.1700491
Published in The Journal of Chemical Physics
Authors William W. Wood, Wildon Fickett, John G. Kirkwood

The problem of the absolute configuration of optically active molecules is investigated with the aid of the Kirkwood theory of optical rotatory power. Absolute configurations are assigned to the enantiomorphs of 2,3-epoxybutane and 1,2-dichloropropane. The assignments are consistent with the established experimental configurational relationships between these compounds. The Fischer convention is confirmed as a structurally correct representation of absolute configuration. The magnitudes of the calculated rotations of the compounds are in reasonably good agreement with experiment. The theory accounts satisfactorily for the effect of temperature and solvent on the optical rotation of 1,2-dichloropropane.