Unusual Racemization of Tertiary P-Chiral Ferrocenyl Phosphines

6Citations
Citations of this article
12Readers
Mendeley users who have this article in their library.

This article is free to access.

Abstract

Tertiary phosphines are generally known to withstand inversion under moderate conditions. In this work, a remarkable racemization process of three P-chiral ferrocenyl phosphines is reported. Subjected to conventional column chromatography as highly enantioenriched compounds, they greatly experienced racemization when collected at the column outlet within minutes. Initially, attention was drawn to this unusual inversion behavior after observing that the superb enantiomeric excess of these ligands (>95 % ee in all cases) was almost lost in their corresponding ruthenium(II) complexes. Successively excluding possible racemization causes, these P-chiral ferrocenyl phosphines were found to undergo a significant, acid-catalyzed racemization process at room temperature within a few minutes. This process is mainly observed during standard column chromatography by using conventional silica or alumina, but can also be triggered deliberately by addition of certain acids. Therefore, the stereochemical preservation of P-chiral phosphines during their purification may per se not always be guaranteed, since column chromatography is the most frequently used technique for purifying such types of compounds.

Cite

CITATION STYLE

APA

Popp, J., Hanf, S., & Hey-Hawkins, E. (2020). Unusual Racemization of Tertiary P-Chiral Ferrocenyl Phosphines. Chemistry - A European Journal, 26(26), 5765–5769. https://doi.org/10.1002/chem.202000218

Register to see more suggestions

Mendeley helps you to discover research relevant for your work.

Already have an account?

Save time finding and organizing research with Mendeley

Sign up for free