Unusual Racemization of Tertiary P ‐Chiral Ferrocenyl Phosphines

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.

Standort
Deutsche Nationalbibliothek Frankfurt am Main
Umfang
Online-Ressource
Sprache
Englisch

Erschienen in
Unusual Racemization of Tertiary P ‐Chiral Ferrocenyl Phosphines ; volume:26 ; number:26 ; year:2020 ; pages:5765-5769 ; extent:5
Chemistry - a European journal ; 26, Heft 26 (2020), 5765-5769 (gesamt 5)

Urheber
Popp, John
Hanf, Schirin
Hey-Hawkins, Evamarie

DOI
10.1002/chem.202000218
URN
urn:nbn:de:101:1-2022060511164497840733
Rechteinformation
Open Access; Der Zugriff auf das Objekt ist unbeschränkt möglich.
Letzte Aktualisierung
15.08.2025, 07:23 MESZ

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